#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int lcm(int a, int b) { return a / gcd(a, b) * b; }
int main() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  int g = gcd(a, b);
  a /= g;
  b /= g;
  g = gcd(c, d);
  c /= g;
  d /= g;
  int aa = a, bb = b, cc = c, dd = d;
  int l = lcm(a, c);
  g = l / a;
  b *= g;
  g = l / c;
  d *= g;
  int x, y, xx, yy;
  x = b - d;
  y = b;
  g = gcd(x, y);
  x /= g;
  y /= g;
  l = lcm(bb, dd);
  g = l / bb;
  aa *= g;
  g = l / dd;
  cc *= g;
  xx = aa - cc;
  yy = aa;
  g = gcd(xx, yy);
  xx /= g;
  yy /= g;
  if (xx < 0 || yy < 0)
    cout << x << "/" << y << endl;
  else
    cout << xx << "/" << yy << endl;
  return 0;
}
