#include <bits/stdc++.h>
using namespace std;
int a, b, c, d;
long long gcd(long long x, long long y) {
  if (x == 0) return y;
  return gcd(y % x, x);
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> a >> b >> c >> d;
  long long x1 = a * b * c - a * a * d, y1 = c;
  long long x2 = a * b * d - b * b * c, y2 = d;
  if ((long long)x1 * (long long)y2 < (long long)x2 * (long long)y1) {
    swap(x1, x2);
    swap(y1, y2);
  }
  y1 *= a * b;
  long long g = gcd(x1, y1);
  cout << x1 / g << "/" << y1 / g << endl;
  return 0;
}
