#include <bits/stdc++.h>
using namespace std;
double pi = acos(-1);
const long long N = (1e2) + 100, mod = 1e9 + 7, OO = 1e9;
int gcd(int a, int b) { return (b == 0) ? a : gcd(b, a % b); }
int main() {
  int a, b, c, d, x, y, g;
  scanf("%d %d %d %d", &a, &b, &c, &d);
  if (a * d <= b * c) {
    x = b * c - a * d;
    y = b * c;
    g = gcd(x, y);
  } else if (a * d > b * c) {
    x = a * d - b * c;
    y = a * d;
    g = gcd(x, y);
  }
  printf("%d/%d\n", x / g, y / g);
  return 0;
}
