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