#include <bits/stdc++.h>
using namespace std;
unsigned long long gcd(unsigned long long x, unsigned long long y) {
  while (x) {
    unsigned long long r = y % x;
    y = x;
    x = r;
  }
  return y;
}
unsigned long long lcm(unsigned long long x, unsigned long long y,
                       unsigned long long z) {
  x /= z;
  return x * y;
}
int main() {
  unsigned long long t, w, b, mn, ans = 0;
  cin >> t >> w >> b;
  mn = min(w, b);
  mn--;
  unsigned long long temp = t, g = gcd(w, b);
  temp /= w;
  temp *= g;
  temp /= b;
  if (temp == 0) {
    mn = min(mn, t);
    unsigned long long q = gcd(mn, t);
    cout << mn / q << '/' << t / q;
  } else {
    unsigned long long r = lcm(w, b, g);
    ans = mn;
    ans += ((mn + 1) * ((t / r) - 1));
    ans += min(t - (t / r) * r, mn);
    ans++;
    unsigned long long p = gcd(ans, t);
    cout << ans / p << '/' << t / p;
  }
}
