#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  int x, y, i;
  if (b * c > a * d) {
    x = b * c - a * d;
    y = b * c;
  } else {
    x = a * d - b * c;
    y = a * d;
  }
  while (1) {
    int k = 0;
    for (i = 2; i <= x; i++) {
      if (x % i == 0 && y % i == 0) {
        x = x / i;
        y = y / i;
        k++;
      }
    }
    if (k == 0) break;
  }
  if (x == 0)
    cout << x << "/"
         << "1";
  else
    cout << x << "/" << y;
  return 0;
}
