#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (a % b == 0)
    return b;
  else
    return gcd(b, a % b);
}
int a, b, c, d;
int main() {
  scanf("%d %d %d %d", &a, &b, &c, &d);
  int t, bo;
  if (a * d >= c * b) {
    t = b * c;
    bo = d * a;
  } else {
    t = a * d;
    bo = c * b;
  }
  t = bo - t;
  int cc = gcd(t, bo);
  printf("%d/%d\n", t / cc, bo / cc);
}
