#include <bits/stdc++.h>
using namespace std;
const long long INF = 9223372036854775807LL;
long long t, w, b;
int wei(long long);
void init();
void work();
long long gcd(long long, long long);
void read(long long&);
int main() {
  init();
  work();
  return 0;
}
int wei(long long x) {
  int ans = 0;
  while (x) x /= 10, ans++;
  return ans;
}
long long gcd(long long a, long long b) {
  return (b == 0) ? (a) : gcd(b, a % b);
}
void work() {
  long long minn = min(w, b);
  long long d = gcd(w, b);
  long long lcm;
  if ((INF / b) < (w / d))
    lcm = INF;
  else
    lcm = (w / d) * b;
  long long p = t / lcm;
  long long ans = p * minn - 1;
  long long yu = t % lcm;
  ans += min(yu + 1, minn);
  d = gcd(ans, t);
  ans /= d;
  t /= d;
  printf("%I64u/%I64u\n", ans, t);
}
void init() { read(t), read(w), read(b); }
void read(long long& x) {
  long long f = 1;
  char ch = getchar();
  x = 0;
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  x *= f;
}
