#include <bits/stdc++.h>
long long gcd(long long a, long long b) {
  if (a < b) return gcd(b, a);
  if (b) return gcd(b, a % b);
  return a;
}
int main() {
  long long t, w, b, lcm, ans, temp;
  while (~scanf("%I64d%I64d%I64d", &t, &w, &b)) {
    lcm = w / gcd(w, b) * b;
    if (t / w * gcd(w, b) / b)
      ans = (t / lcm) * ((w) < (b) ? (w) : (b)) +
            (((((w) < (b) ? (w) : (b)) - 1)) < ((t % lcm))
                 ? ((((w) < (b) ? (w) : (b)) - 1))
                 : ((t % lcm)));
    else
      ans = (((((w) < (b) ? (w) : (b)) - 1)) < (t)
                 ? ((((w) < (b) ? (w) : (b)) - 1))
                 : (t));
    temp = gcd(ans, t);
    printf("%I64d/%I64d\n", ans / temp, t / temp);
  }
  return 0;
}
