#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  int c;
  c = a % b;
  while (c) {
    a = b;
    b = c;
    c = a % b;
  }
  return b;
}
int lcm(int a, int b) { return (a * b) / gcd(a, b); }
int main() {
  int a, b, c, d, tem;
  cin >> a >> b >> c >> d;
  tem = lcm(b, d);
  a *= tem / b;
  c *= tem / d;
  if (a > c)
    cout << ((a - c) / gcd(a - c, a)) << "/" << (a / gcd(a - c, a)) << endl;
  else
    cout << ((c - a) / gcd(c - a, c)) << "/" << (c / gcd(c - a, c)) << endl;
  return 0;
}
