#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
const int M = maxn * 100;
int gcd(int a, int b) { return b == 0 ? a : gcd(b, a % b); }
int lcm(int a, int b) { return a / gcd(a, b) * b; }
int main() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  a *= d;
  b *= c;
  if (a > b) swap(a, b);
  a = b - a;
  cout << a / gcd(a, b) << '/' << b / gcd(a, b) << endl;
}
