#include <bits/stdc++.h>
using namespace std;
int cpt(int a, int b) {
  int c;
  while (a % b != 0) {
    c = a % b;
    a = b;
    b = c;
  }
  return b;
}
int main() {
  int t1, t2, t3, t4;
  scanf("%d%d%d%d", &t1, &t2, &t3, &t4);
  if (t4 * t1 - t2 * t3 < 0) {
    int c = cpt(t3 * t2 - t4 * t1, t3 * t2);
    printf("%d/%d", (t3 * t2 - t4 * t1) / c, t3 * t2 / c);
  } else {
    int c = cpt(t4 * t1 - t3 * t2, t4 * t1);
    printf("%d/%d", (t4 * t1 - t3 * t2) / c, t4 * t1 / c);
  }
  return 0;
}
