#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }
int main() {
  int a, b, c, d;
  while (scanf("%d%d%d%d", &a, &b, &c, &d) != EOF) {
    if (a * d < c * b) {
      int g = gcd(b * c, b * c - d * a);
      printf("%d/%d\n", (b * c - d * a) / g, b * c / g);
    } else {
      int g = gcd(a * d, a * d - b * c);
      printf("%d/%d\n", (a * d - b * c) / g, a * d / g);
    }
  }
  return 0;
}
