#include <bits/stdc++.h>
using namespace std;
long long int gcd(long long int n, long long int m) {
  if (m == 0)
    return n;
  else
    return gcd(m, n % m);
}
int main() {
  long long int a, b, c, d, i, p, q, r, s, t;
  cin >> a >> b >> c >> d;
  p = a * d;
  q = b * c;
  if (p == q) {
    cout << 0 << "/" << 1;
    return 0;
  } else {
    r = abs(p - q);
    s = max(p, q);
    t = gcd(r, s);
    cout << r / t << "/" << s / t;
    return 0;
  }
}
