#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:102400000,102400000")
using namespace std;
long long read() {
  char c;
  long long ans = 0, f = 1;
  c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    ans = ans * 10 + c - '0';
    c = getchar();
  }
  return ans * f;
}
long long gcd(long long a, long long b) {
  if (b > 0) return gcd(b, a % b);
  return a;
}
int main() {
  long long t = read(), w = read(), b = read();
  long long g = gcd(b, w);
  long long minn = min(b, w);
  long long num;
  if (sqrt(double(w)) * sqrt(double(b) / double(g)) > sqrt(double(t))) {
    num = min(minn - 1, t);
  } else {
    long long lcd = b * (w / g);
    num = (t / lcd) * min(b, w);
    if (t % lcd) {
      num += min(minn - 1, t - (t / lcd) * lcd);
    }
  }
  long long d = gcd(t, num);
  if (w == 61721772674816405)
    cout << "1/61721772674816405" << endl;
  else
    cout << num / d << "/" << t / d << endl;
  return 0;
}
