#include <bits/stdc++.h>
using namespace std;
int a, b, c, d;
int N, D, t;
int gcd(int a, int b) {
  if (a % b) return gcd(b, a % b);
  return b;
}
int main() {
  scanf("%d%d%d%d", &a, &b, &c, &d);
  N = c * b, D = a * d;
  if (N > D) swap(N, D);
  N = D - N;
  t = gcd(N, D);
  if (t != 1) N /= t, D /= t;
  printf("%d/%d\n", N, D);
  return 0;
}
