#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
double gcd(double a, double b) {
  while (a != b) {
    if (a > b) {
      a = a - b;
    } else {
      b = b - a;
    }
  }
  return a;
}
int main() {
  double a, b, c, d;
  int temp1, temp2;
  cin >> a >> b >> c >> d;
  if (c >= a && d >= b) {
    if (c / a > b / d) {
      temp1 = b * c - d * a;
      temp2 = b * c;
    } else {
      temp1 = a * b - c * d;
      temp2 = a * b;
    }
  } else {
    if (a / c < b / d) {
      temp1 = b * c - a * d;
      temp2 = b * c;
    } else {
      temp1 = a * d - b * c;
      temp2 = a * d;
    }
  }
  if (temp1 == 0) {
    cout << temp1 << "/1";
  } else {
    double gcdd = gcd(temp1, temp2);
    cout << fixed << setprecision(0) << temp1 / gcdd << "/" << fixed
         << setprecision(0) << temp2 / gcdd;
  }
}
