#include <bits/stdc++.h>
int gcd(int a, int b) {
  int c = a % b;
  while (c != 0) {
    a = b;
    b = c;
    c = a % b;
  }
  return b;
}
int main() {
  int a, b, c, d;
  scanf("%d%d%d%d", &a, &b, &c, &d);
  int ansa, ansb;
  if (b * c >= a * d) {
    ansa = b * c - a * d;
    ansb = b * c;
  } else {
    ansa = a * d - b * c;
    ansb = a * d;
  }
  int ansc = gcd(ansa, ansb);
  printf("%d/%d\n", ansa / ansc, ansb / ansc);
  return 0;
}
