Fraction addition

gistfile1.txt

#include <stdio.h>

int main()
{
    int a, b, c, d;
    printf("Enter fraction 1(numerator denominator) \n");
    scanf("%d %d", &a,&b);
    printf("Enter fraction 2(numerator denominator) \n");
    scanf("%d %d", &c, &d);
    if (b == 0 || d == 0){
        printf("Math Error");
        return 0;
    }
    if (b == d){
        if(b / d *d != b){
            printf("%d / %d \n", a + c, b);
        }
        else{
            printf("%d", (a+c) / b);
        }
    }
    else {
        int up, down;
        up = a*d+c*b;
        down =b*d;
        if (up / down * up != up){
        printf("%d / %d \n", up, down);
        }
        else{
            printf("%d", up/down);
        }
    }
    return 0;
}