#include <bits/stdc++.h>
using namespace std;
const int N = 1e14;
const int M = 1e5 + 5;
long long gcd(long long a, long long b) {
  if (a == 0)
    return b;
  else
    return gcd(b % a, a);
}
long long a[M];
long long dp[M];
map<long long, long long> m;
vector<pair<long long, long long> > v;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  long long a, b, c, d, up, dwn, t;
  cin >> a >> b >> c >> d;
  if (a * d <= b * c) {
    up = b * c - a * d;
    dwn = b * c;
  } else if (a * d > b * c) {
    up = a * d - b * c;
    dwn = a * d;
  }
  t = gcd(up, dwn);
  cout << up / t << "/" << dwn / t;
}
