#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 t, a, b, w, fz, fm, xx;
double v;
int main() {
  scanf("%lld%lld%lld", &t, &a, &b);
  w = gcd(a, b);
  fm = t;
  xx = min(a, b);
  v = (double)a / w * b;
  if (v > (double)t) {
    fz = min(xx - 1, t);
  } else {
    a /= w;
    a *= b;
    w = t / a;
    t -= w * a;
    fz = w * xx + min(xx - 1, t);
  }
  w = gcd(fz, fm);
  fz /= w;
  fm /= w;
  printf("%lld/%lld", fz, fm);
}
