#include <bits/stdc++.h>
using namespace std;
int GCD(int a, int b) {
  while (a && b)
    if (a > b)
      a %= b;
    else
      b %= a;
  return a + b;
}
int main(int argc, char *argv[]) {
  int a, b, c, d, x, A, B;
  double X, Y;
  cin >> a >> b >> c >> d;
  if (b * c >= a * d) {
    x = GCD(a * b * c - a * a * d, c);
    A = (a * b * c - a * a * d) / x;
    B = c * a * b / x;
    x = GCD(A, B);
    A /= x;
    B /= x;
    cout << A << '/' << B;
  } else {
    x = GCD(b * a * d - b * b * c, d);
    A = (b * a * d - b * b * c) / x;
    B = d * a * b / x;
    x = GCD(A, B);
    A /= x;
    B /= x;
    cout << A << '/' << B;
  }
  return EXIT_SUCCESS;
}
