#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e6 + 3;
const int INFI = 1e9 * 2;
const long long LINFI = 1e17;
const double pi = acos(-1.0);
const double s2 = sqrt(2.0);
const int N = 222;
const int M = 11;
const int move[8][2] = {1, 0, -1, 0, 0, 1, 0, -1, 1, 1, 1, -1, -1, 1, -1, -1};
int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }
int main() {
  int a, b, c, d, p, q, m, x, y;
  while (scanf("%d%d%d%d", &a, &b, &c, &d) != EOF) {
    m = c * d / gcd(c, d);
    a *= m;
    b *= m;
    x = a / c;
    y = b / d;
    if (x >= y) {
      q = a;
      p = a - y * c;
    } else {
      q = b;
      p = b - x * d;
    }
    m = gcd(p, q);
    q /= m;
    p /= m;
    printf("%d/%d\n", p, q);
  }
  return 0;
}
