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