#include <bits/stdc++.h>
using namespace std;
const double PI = 2 * asin(1.0);
const int INF = 1000000000;
const double EPS = 1e-10;
inline int cmp(double x, double y = 0, double tol = EPS) {
  return (x <= y + tol) ? (x + tol < y) ? -1 : 0 : 1;
}
inline long long gcd(long long a, long long b) {
  return b == 0 ? abs(a) : gcd(b, a % b);
}
inline long long lcm(long long a, long long b) {
  return a == 0 || b == 0 ? 0 : abs(a * (b / gcd(a, b)));
}
int main() {
  long long a, b, c, d, ra, rb, temp;
  cin >> a >> b >> c >> d;
  double X = (double)d / (double)b, Y = (double)c / (double)a;
  if (X < Y) {
    ra = b * c - a * d;
    rb = b * c;
    temp = gcd(ra, rb);
    ra /= temp;
    rb /= temp;
    cout << ra << "/" << rb << endl;
  } else {
    ra = a * d - c * b;
    rb = a * d;
    temp = gcd(ra, rb);
    ra /= temp;
    rb /= temp;
    cout << ra << "/" << rb << endl;
  }
  return 0;
}
