#include <bits/stdc++.h>
int const N = 2 * 1e5 + 5, M = 1005;
using namespace std;
long long gcd(long long a, long long b) {
  if (!a) return b;
  return gcd(b % a, a);
}
void getR(long long a, long long b) {
  long long g = gcd(a, b);
  cout << a / g << "/" << b / g;
  exit(0);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long a, b, c, d;
  cin >> a >> b >> c >> d;
  if ((long double)a / b > (long double)c / d) getR((a * d - b * c), a * d);
  if ((long double)a / b < (long double)c / d) getR((b * c - a * d), b * c);
  cout << 0 << "/" << 1;
  return 0;
}
