#include <bits/stdc++.h>
using namespace std;
const int mod = 1000000007;
int power(int x, int y) {
  int res = 1;
  x = x % mod;
  while (y > 0) {
    if (y & 1) res = (res * x) % mod;
    y = y >> 1;
    x = (x * x) % mod;
  }
  return res;
}
int ncr(int n, int r) {
  int res = 1;
  if (r > n - r) r = n - r;
  for (int i = 0; i < r; i++) {
    res *= (n - i);
    res /= (i + 1);
  }
  return res;
}
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 max(int a, int b) {
  int ans = a > b ? a : b;
  return ans;
}
int min(int a, int b) {
  int ans = a < b ? a : b;
  return ans;
}
int main() {
  long long a, b, c, d, p, q, t, r;
  cin >> a >> b >> c >> d;
  p = a * d - b * c;
  q = a * d;
  r = b * c;
  if (1.0 * b / d < 1.0 * a / c) {
    t = gcd(p, q);
    cout << p / t << "/" << q / t;
  } else {
    t = gcd(r - q, r);
    cout << (r - q) / t << "/" << r / t;
  }
}
