import java.util.*;
/*

fibonacci method
aP[2][0]
aP[3][0] + aP[2][1]
aP[4][0] + aP[3][1] + aP[2][2]
aP[5][0] + aP[4][1] + aP[3][2]
aP[6][0] + aP[5][1] + aP[4][2] + aP[3][3]
aP[7][0] + aP[6][1] + aP[5][2] + aP[4][3]

*/

public class PascalFibonacci{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long[][] arrPascal = new long[65][65];
        for (int i = 0; i < arrPascal[i].length - 1; i++) {
            for (int j = 0; j < arrPascal.length - 1; j++) {
                arrPascal[j][i] = choose(j,i);
            }
        }

        System.out.print("Input row index: ");
        int rowIndex = sc.nextInt();
        System.out.print("Input column index: ");
        int colIndex = sc.nextInt();
        // try{
        //  Math.addExact();
        // }
        // catch Exception e{
        //  choose()
        // }
        int total = 0;
        int i = 0;
        int j = rowIndex;
        while (i<colIndex && j>0){
            total += arrPascal[i][j];
            i++;
            j--;
        }

        System.out.println("-----------------------");
        System.out.println("Fibonacci(" + i + ")     = " + total);

        // for (int i = 0; i<colIndex+1; i++) {
        //  System.out.print("arrPascal[" + (rowIndex-i) +"][" + i + "]   = ");
        //  System.out.printf("%d2 arrPascal[");
        // }

    }

    public static long choose(long n,long r){
        long nFact = 1;
        long rFact = 1;
        long nrFact = 1;
        for (long i = 2; i<=n; i++) {
            nFact *= i;
        }
        for (long i = 2; i<=r; i++) {
            rFact *= i;
        }
        for (long i = 2; i<=(n-r); i++) {
            nrFact *= i;
        }
        long num = nFact;
        long denom = rFact*nrFact;
        // System.out.println(num + ", " + denom);
        // Starts dying when num = 67
        //if(denom == 0) System.out.println(n);
        long nCr = num/denom;


        return nCr;
    }
}