#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) { return b == 0 ? a : gcd(b, a % b); }
int check(long long a, int b) {
  int bita = 0, bitb = 0;
  long long aa = a, bb = b;
  while (aa) {
    bita++;
    aa /= 10;
  }
  while (bb) {
    bitb++;
    bb /= 10;
  }
  if (bita + bitb > 19) return 0;
  return 1;
}
int main() {
  long long t, w, b;
  while (scanf("%I64d%I64d%I64d", &t, &w, &b) != EOF) {
    long long g1 = gcd(w, b);
    long long ans = 0, lcm;
    if (check(w / g1, b)) {
      lcm = w / g1 * b;
    }
    ans += t / lcm * min(w, b);
    ans += min(t % lcm, min(w, b) - 1);
    long long g2 = gcd(ans, t);
    ans /= g2;
    t /= g2;
    printf("%I64d/%I64d\n", ans, t);
  }
  return 0;
}
