#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) { return b == 0 ? a : gcd(b, a % b); }
long long lcm(long long a, long long b, long long t) {
  if ((long double)a / gcd(a, b) * b >= t + 1) {
    return t + 1;
  }
  return a / gcd(a, b) * b;
}
int main() {
  long long a, b, c, i, ans = 0;
  cin >> a >> b >> c;
  if (b < c) swap(b, c);
  ans += (c - 1);
  long long tmp = lcm(b, c, a);
  ans += c * (a / tmp - 1);
  if (a % tmp < (c))
    ans += (a % tmp + 1);
  else
    ans += c;
  printf("%I64d/%I64d\n", ans / gcd(ans, a), a / gcd(ans, a));
}
