import java.util.Scanner;
public class Laba2_2 {
    final static Scanner scan = new Scanner(System.in);
    final static int MAX_VALUE = 1000;
    static int checkException(int number){
        boolean isIncorrect;
        number = 0;
        do{
            isIncorrect = false;
            try {
                number = Integer.parseInt(scan.nextLine());
            }
            catch (NumberFormatException e) {
                System.err.println("Введите натуральное число!");
                isIncorrect = true;
            }
            if (!isIncorrect && (number < 1 || number > MAX_VALUE)) {
                System.err.println("Введите число в диапахоне от 1 до 100");
                isIncorrect = true;
            }
        } while (isIncorrect);
        return number;
    }
    static int inputNumber(String text) {
        int number = 0;
        System.out.println("Введите " + text + " дроби: ");
        number = checkException(number);
        return number;
    }
    static int findNOD(int firstNumber, int secondNumber){
        while (secondNumber != 0) {
            if (firstNumber > secondNumber)
                firstNumber = firstNumber - secondNumber;
            else
                secondNumber = secondNumber - firstNumber;
        }
        return firstNumber;
    }
    static int findNOK(int firstNumber, int secondNumber){
        int nod = findNOD(firstNumber, secondNumber);
        int nok = (firstNumber * secondNumber) / nod;
        return nok;
    }
    static void checkDivisors(int numerator, int denominator){
        int divisors;
        boolean isIncorrect;
        do {
            isIncorrect = false;
            divisors = findNOD(numerator, denominator);
            if (divisors > 1) {
                System.out.println("Дробь должна быть несократимой!");
                numerator = inputNumber("числитель");
                denominator = inputNumber("знаменатель");
                isIncorrect = true;
            }
        }while(isIncorrect);
    }
    static int takeDenominator(int n, int q){
        int denominator = findNOK(n, q);
        return denominator;
    }
    static int takeNumerator(int denominator, int m, int n, int p, int q){
        int numerator = (denominator / n * m) + (denominator / q * p);
        return numerator;
    }
    static int[] cutFraction(int numerator, int denominator){
        int nod = findNOD(numerator, denominator);
        int finalNumerator = numerator / nod;
        int finalDenominator = denominator / nod;
        int[] arr = {finalNumerator, finalDenominator};
        return arr;
    }
    static void outputFraction(int[] arr){
        System.out.println("Сумма дробей: " + arr[0] + "/" + arr[1]);
    }
    public static void main(String[] args) {
        System.out.println("Программа считает сумму двух обыкновенных несократимых дробей");
        int m;
        int n;
        m = inputNumber("числитель первой");
        n = inputNumber("знаменатель первой");
        checkDivisors(m, n);
        int p;
        int q;
        p = inputNumber("числитель второй");
        q = inputNumber("знаменатель второй");
        checkDivisors(p, q);
        scan.close();
        int denominator;
        int numerator;
        denominator = takeDenominator(n, q);
        numerator = takeNumerator(denominator, m, n, p, q);
        int[] arr = cutFraction(numerator, denominator);
        outputFraction(arr);
    }
}