#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() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  int res1 = abs(a * d - b * c), res2 = max(a * d, c * b);
  int res3 = gcd(res1, res2);
  cout << res1 / res3 << "/" << res2 / res3 << "\n";
  return 0;
}
