#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (a < b) return gcd(b, a);
  if (b == 0) return a;
  return gcd(b, a % b);
}
int main() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  double p, q;
  p = (1.0 * a) / c;
  q = (1.0 * b) / d;
  if (p < q) {
    int num = (b * c - a * d);
    int den = b * c;
    int g = (gcd(num, den));
    num = num / g;
    den = den / g;
    cout << num << '/' << den << endl;
  } else {
    int num = abs(b * c - a * d);
    int den = a * d;
    int g = (gcd(num, den));
    num = num / g;
    den = den / g;
    cout << num << '/' << den << endl;
  }
  return 0;
}
