#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) {
  if (a < b) swap(a, b);
  while (b) swap(a, b), b %= a;
  return a;
}
int main() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  int f, g;
  if (c * b <= a * d)
    f = a * d - c * b, g = a * d;
  else
    f = c * b - a * d, g = c * b;
  long long GCD = gcd(f, g);
  cout << f / GCD << "/" << g / GCD;
  return 0;
}
