#include <bits/stdc++.h>
using namespace std;
const unsigned long long N = 1e10;
int getLen(unsigned long long a) {
  int len = 0;
  while (a) {
    len++;
    a /= 10;
  }
  return len;
}
unsigned long long gcd(unsigned long long a, unsigned long long b) {
  return b == 0 ? a : gcd(b, (a % b));
}
unsigned long long lcm(unsigned long long a, unsigned long long b) {
  unsigned long long t = gcd(a, b);
  if (getLen(a / t) + getLen(b) > 22) return 0;
  return a / gcd(a, b) * b;
}
int main() {
  unsigned long long t, w, b;
  unsigned long long p;
  cin >> t >> w >> b;
  if (w == b) {
    printf("1/1\n");
    return 0;
  }
  unsigned long long mi = min(w, b);
  if (t < mi) {
    printf("1/1\n");
    return 0;
  }
  unsigned long long l = lcm(w, b);
  if (l <= 0)
    p = mi - 1;
  else {
    unsigned long long x = t / l;
    if (x == 0) {
      p = mi - 1;
    } else {
      p = min(mi, t - x * l + 1) + x * mi - 1;
    }
  }
  unsigned long long d = gcd(p, t);
  printf("%lld/%lld\n", p / d, t / d);
  return 0;
}
