#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  if (a * d < c * b) {
    int g = gcd(b * c - a * d, b * c);
    cout << ((b * c - a * d) / g) << "/" << (b * c / g) << endl;
  } else {
    int g = gcd(a * d - b * c, a * d);
    cout << ((a * d - b * c) / g) << "/" << (a * d / g) << endl;
  }
  return 0;
}
