#include <bits/stdc++.h>
using namespace std;
int nod(int x, int y) {
  while (x != 0 && y != 0) {
    if (x > y)
      x = x % y;
    else
      y = y % x;
  }
  if (x == 0)
    return y;
  else
    return x;
}
int main() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  if (a * d == c * b) {
    cout << "0/1" << endl;
    return 0;
  }
  int x, y;
  if (a * d > b * c) {
    x = a * d - b * c;
    y = a * d;
  } else {
    x = b * c - a * d;
    y = b * c;
  }
  int k = nod(x, y);
  x = x / k;
  y = y / k;
  cout << x << "/" << y << endl;
  return 0;
}
