#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  int rem = a % b;
  while (rem != 0) {
    a = b;
    b = rem;
    rem = a % b;
  }
  return b;
}
int main() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  int mul1 = 0, mul2 = 0;
  int res1 = 0, res2 = 0;
  int ans = 0;
  mul1 = a * d;
  mul2 = c * b;
  if (mul1 <= mul2) {
    res1 = mul2 - mul1;
    res2 = mul2;
  } else {
    res1 = mul1 - mul2;
    res2 = mul1;
  }
  ans = gcd(res1, res2);
  if (gcd((res1 / ans), (res2 / ans)) == 1) {
    cout << (res1 / ans) << "/" << (res2 / ans) << endl;
  } else {
    return -1;
  }
  return 0;
}
