#include <bits/stdc++.h>
using namespace std;
int a, b, c, d;
int gcd(int a, int b) {
  int t;
  while (b) {
    t = a % b;
    a = b;
    b = t;
  }
  return a;
}
int lcm(int a, int b) { return a / gcd(a, b) * b; }
int main() {
  scanf("%d%d%d%d", &a, &b, &c, &d);
  int ac = lcm(a, c);
  int bd = lcm(b, d);
  int p, q, g;
  if (ac / a * b <= d * ac / c) {
    p = ac / a * b;
    q = d * ac / c;
    g = gcd(p, q);
    p /= g;
    q /= g;
  }
  if (ac / c * d <= b * ac / a) {
    p = ac / c * d;
    q = b * ac / a;
    g = gcd(p, q);
    p /= g;
    q /= g;
  }
  if (bd / b * a <= c * bd / d) {
    p = bd / b * a;
    q = c * bd / d;
    g = gcd(p, q);
    p /= g;
    q /= g;
  }
  if (bd / d * c <= a * bd / b) {
    p = bd / d * c;
    q = a * bd / b;
    g = gcd(p, q);
    p /= g;
    q /= g;
  }
  printf("%d/%d", q - p, q);
  return 0;
}
