public class Solution {

    private static int change;
    private static int mIndex;
    private static int mSubIndex;
    private static int round;
    private static boolean isMyTurn;
    private static StringBuilder current, winner;
    private static char player1 = 'x';
    private static char player2 = 'x';
    private static char player0 = 'x';


    public static void main(String[] args) {

        System.out.println("Changed: " + handFormationChange(5, 2, "RP") + " times");


    }

    private static int handFormationChange(int n, int a, String formation) {

        //Check if the given string is Empty
        if (formation.length() < 1) {
            return 0;
        } else {
            //Extract all empty spaces from the given string (if any)
            formation = formation.replaceAll("\\s+", "");
            current = new StringBuilder(formation);
            winner = new StringBuilder();

            //Set the index to the given initial position
            mIndex = a;

            //insert arbitrary char in my position to complete the number of players
            current.insert(a, 'x');
            System.out.println(current);
            //Determine my first formation by checking the status and position of my first opponent
            if (((a + 1) % 2 == 0) && (a - 1 >= 0)) {
                player0 = pickWinnerAgainst(current.charAt(a - 1));
            } else if (((a + 1) % 2 != 0) && (a < current.length() - 1)) {
                player0 = pickWinnerAgainst(current.charAt(a + 1));
            }

            //As long as no final winner yet..
            while (current.length() > 1) {
                round++;

                //Start the competition..
                for (int i = 0; i < current.length(); i += 2) {

                    //if the first player of any pairs is me
                    if (i == mIndex) {
                        //and I am the last player in the line - hasn't chosen a formation yet
                        if (player0 == 'x') {
                            //and there at least another opponent to play against yet
                            if (winner.length() > 0) {
                                //choose my first winning formation and qualify
                                player0 = pickWinnerAgainst(winner.charAt(0));
                                winner.append(player0);
                                continue;
                            } else {
                                //if I'm the only remaining player .. I win with any formation
                                player0 = 'S';
                                winner.append(player0);
                                continue;
                            }

                        } else {
                            //If I am the last player in the line with a formation chosen
                            player1 = player0;
                            //Ask to pick a winning formation for me as a first player in pair
                            mSubIndex = 1;
                            isMyTurn = true;
                        }

                    } else {
                        //If I'm not one of the pair
                        player1 = current.charAt(i);
                    }

                    //if the second player of any pairs is me
                    if ((i + 1) == mIndex) {
                        player2 = player0;
                        //Ask to pick a winning formation for me as a second player in pair
                        mSubIndex = 2;
                        isMyTurn = true;
                    } else {
                        //If I'm not one of the pair & there's enough players in the line, pick the second player
                        if ((i + 1) <= current.length() - 1) {
                            player2 = current.charAt(i + 1);
                        } else {
                            //if I'm the first player in pair and the last player
                            if (i == mIndex) {
                                //qualify me
                                winner.append(player1);
                                //save my new position for the next round
                                mIndex = winner.length() - 1;
                                isMyTurn = false;
                                continue;
                                //if the last player has no opponent and wasn't me, qualify him for the next round
                            } else {
                                winner.append(player1);
                                continue;
                            }
                        }
                    }

                    // if I'm in the pair
                    if (isMyTurn) {
                        //and I'm player1 in pair
                        if (mSubIndex == 1) {
                            insertWinner(player1, player2);
                            //and I'm player2 in pair
                        } else if (mSubIndex == 2) {
                            insertWinner(player2, player1);
                        }
                        //if I'm not in the pair
                    } else {
                        if (player1 == 'P' && player2 == 'R') {
                            winner.append(player1);
                        } else if (player1 == 'R' && player2 == 'P') {
                            winner.append(player2);
                        } else if (player1 == 'S' && player2 == 'P') {
                            winner.append(player1);
                        } else if (player1 == 'P' && player2 == 'S') {
                            winner.append(player2);
                        } else if (player1 == 'R' && player2 == 'S') {
                            winner.append(player1);
                        } else if (player1 == 'S' && player2 == 'R') {
                            winner.append(player2);
                        }
                    }

                }

                //start a new round with the previous round winners
                current = new StringBuilder(winner);
                winner.setLength(0);
                winner = new StringBuilder();
            }

            return change;
        }

    }

    //check if my current formation help me winning
    private static boolean isWinning(char m, char n) {
        if (m == 'P' && n == 'R') {
            return true;
        } else if (m == 'R' && n == 'P') {
            return false;
        } else if (m == 'S' && n == 'P') {
            return true;
        } else if (m == 'P' && n == 'S') {
            return false;
        } else if (m == 'R' && n == 'S') {
            return true;
        } else if (m == 'S' && n == 'R') {
            return false;
            //in case of a draw, All lose!
        } else {
            return false;
        }
    }

    //Advice me with the perfect formation to win
    private static char pickWinnerAgainst(char mChar) {
        if (mChar == 'P') {
            return 'S';

        } else if (mChar == 'S') {
            return 'R';
        } else {
            return 'P';
        }


    }

    //Do what's best for me and save my new position in the next round
    private static void insertWinner(char playerA, char playerB) {
        if (isWinning(playerA, playerB)) {
            winner.append(playerA);
            mIndex = winner.length() - 1;
            isMyTurn = false;
        } else {
            player0 = pickWinnerAgainst(playerB);
            winner.append(player0);
            System.out.println(playerA + " -> " + player0 + " @R" + round);
            change++;
            mIndex = winner.length() - 1;
            isMyTurn = false;
        }
    }

}