#include <bits/stdc++.h>
using namespace std;
int maxye(int a, int b) {
  int temp;
  while (a % b) {
    temp = b;
    b = a % b;
    a = temp;
  }
  return b;
}
int main() {
  int a, b, c, d;
  int x, y;
  while (cin >> a >> b >> c >> d) {
    if (a * d >= c * b) {
      x = a * d - c * b;
      y = a * d;
    }
    if (a * d < c * b) {
      x = b * c - a * d;
      y = b * c;
    }
    int z = maxye(x, y);
    cout << x / z << '/' << y / z << endl;
  }
  return 0;
}
