#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
int main() {
  long long a, b, c, d, i, k, j;
  cin >> a >> b >> c >> d;
  if (double(a) / b < double(c) / d) {
    k = b * c - a * d;
    i = b * c;
  } else if (double(a) / b > double(c) / d) {
    k = a * d - b * c;
    i = a * d;
  } else if (double(a) / b == double(c) / d) {
    cout << "0/1";
    return 0;
  }
  j = gcd(i, k);
  cout << k / j << "/" << i / j;
  return 0;
}
