#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) {
  return a % b == 0 ? b : gcd(b, a % b);
}
int main() {
  long long a, b, c, d;
  cin >> a >> b >> c >> d;
  double A = (double)a, B = (double)b, C = (double)c, D = (double)d;
  if (fabs(A / B - C / D) <= 1e-6)
    cout << "0/1" << endl;
  else if (A / B > C / D) {
    long long p = a * d - b * c, q = a * d;
    long long g = gcd(p, q);
    p /= g;
    q /= g;
    cout << p << '/' << q << endl;
  } else {
    long long p = b * c - a * d, q = b * c;
    long long g = gcd(p, q);
    p /= g;
    q /= g;
    cout << p << '/' << q << endl;
  }
  return 0;
}
