#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) {
  while (b) {
    a %= b;
    swap(a, b);
  }
  return a;
}
int main() {
  ios_base::sync_with_stdio(0);
  long long a, b, c, d;
  cin >> a >> b >> c >> d;
  if (b * c == a * d)
    cout << "0/1" << endl;
  else if (b * c > a * d) {
    cout << (b * c - a * d) / gcd(b * c - a * d, b * c) << '/'
         << b * c / gcd(b * c - a * d, b * c) << endl;
  } else
    cout << (a * d - b * c) / gcd(a * d - b * c, a * d) << '/'
         << a * d / gcd(a * d - b * c, a * d) << endl;
  return 0;
}
