12935 - Greatest Common Divisor

#include <stdio.h>

int GCD(int, int);
int main(){
    int a, b;
    scanf("%d %d", &a, &b);
    printf("%d\n", GCD(a, b));
    return 0;
}

int GCD(int a, int b){
    if(b ==0) return a;
    else return GCD(b, a%b);
}
//euclidean algorithm
//basically A=BQ + R
//GCD (A, B) = GCD(B,R)
//GCD (A, 0) = A
//GCD (B, 0) = B