#include <bits/stdc++.h>
using namespace std;
template <class T>
T scan() {
  T t;
  cin >> t;
  return t;
}
int dr[] = {0, -1, 1, 0, -1, 1, -1, 1};
int dc[] = {-1, 0, 0, 1, 1, -1, -1, 1};
long long int gcd(long long int a, long long int b) {
  while (a) {
    swap(a, b);
    a = a % b;
  }
  return b;
}
pair<int, int> calculate(long long int a, long long int b, long long int c,
                         long long int d) {
  long long int ortaq = (a * c) / gcd(a, c);
  long long int vuruq = ortaq / a;
  a *= vuruq, b *= vuruq;
  vuruq = ortaq / c;
  c *= vuruq, d *= vuruq;
  ortaq = gcd(b, d);
  b /= ortaq, d /= ortaq;
  return make_pair(b - d, b);
}
int main() {
  long long int a, b, c, d;
  cin >> a >> b >> c >> d;
  long long int g = gcd(a, b);
  a /= g, b /= g;
  g = gcd(c, d);
  c /= g, d /= g;
  pair<int, int> cavab = calculate(a, b, c, d);
  if (cavab.first < cavab.second && cavab.first >= 0)
    cout << cavab.first << "/" << cavab.second;
  else {
    cavab = calculate(b, a, d, c);
    cout << cavab.first << "/" << cavab.second;
  }
  return 0;
}
