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