#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  int temp;
  while (b) {
    temp = a % b;
    a = b;
    b = temp;
  }
  return (a);
}
int main() {
  int a, b, c, d, n, m;
  scanf("%d%d%d%d", &a, &b, &c, &d);
  int t1 = a * d;
  int t2 = b * c;
  if (t1 > t2) {
    n = t1 - t2;
    m = t1;
  } else {
    n = t2 - t1;
    m = t2;
  }
  if (n == 0)
    printf("0/1\n");
  else if (n == m) {
    printf("1/1\n");
  } else {
    a = gcd(n, m);
    printf("%d/%d\n", n / a, m / a);
  }
  return 0;
}
