#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
int lcm(int a, int b) { return a / gcd(a, b) * b; }
int main() {
  int i, j, k, m, n, a, b, c, d;
  while (~scanf("%d%d%d%d", &a, &b, &c, &d)) {
    int ans1, ans2, ans3, ans4;
    bool flag1 = 0, flag2 = 0;
    i = lcm(a, c);
    j = i / c * d;
    k = i / a * b;
    if (j <= k) ans1 = k - j, ans2 = k, flag1 = 1;
    i = lcm(b, d);
    j = i / d * c;
    k = i / b * a;
    if (j <= k) ans3 = k - j, ans4 = k, flag2 = 1;
    if (flag1 == 0) {
      i = gcd(ans3, ans4);
      if (i) ans3 /= i, ans4 /= i;
      printf("%d/%d\n", ans3, ans4);
      continue;
    }
    if (flag2 == 0) {
      i = gcd(ans1, ans2);
      if (i) ans1 /= i, ans2 /= i;
      printf("%d/%d\n", ans1, ans2);
      continue;
    }
    if (ans1 * ans4 <= ans2 * ans3) {
      i = gcd(ans1, ans2);
      if (i) ans1 /= i, ans2 /= i;
      printf("%d/%d\n", ans1, ans2);
    } else {
      i = gcd(ans3, ans4);
      if (i) ans3 /= i, ans4 /= i;
      printf("%d/%d\n", ans3, ans4);
    }
  }
  return 0;
}
