#include <bits/stdc++.h>
inline int gcd(int a, int b) {
  if (a == 0) return b;
  int q;
  do {
    q = b % a;
    b = a;
    a = q;
  } while (q);
  return b;
}
int main() {
  int a, b, c, d;
  scanf("%d%d%d%d", &a, &b, &c, &d);
  int gg = gcd(a, b);
  a /= gg;
  b /= gg;
  gg = gcd(c, d);
  c /= gg;
  d /= gg;
  int p, q;
  bool solved = false;
  {
    int commonHeight = b * d / gcd(b, d);
    int ScreenWidth = a * commonHeight / b;
    int FilmWidth = c * commonHeight / d;
    if (FilmWidth <= ScreenWidth) {
      solved = true;
      q = ScreenWidth;
      p = ScreenWidth - FilmWidth;
    }
  }
  if (!solved) {
    int commonWidth = a * c / gcd(a, c);
    int ScreenHeight = b * commonWidth / a;
    int FilmHeight = d * commonWidth / c;
    if (FilmHeight <= ScreenHeight) {
      solved = true;
      q = ScreenHeight;
      p = ScreenHeight - FilmHeight;
    }
  }
  if (p == 0)
    puts("0/1");
  else {
    int tmp = gcd(p, q);
    p /= tmp;
    q /= tmp;
    printf("%d/%d\n", p, q);
  }
  return 0;
}
