#include <bits/stdc++.h>
using namespace std;
unsigned long long gcd(unsigned long long a, unsigned long long b) {
  return (b == 0 ? a : gcd(b, a % b));
}
unsigned long long lcm(unsigned long long a, unsigned long long b) {
  return (a * (b / gcd(a, b)));
}
bool CALC(unsigned long long& t, unsigned long long& a, unsigned long long& b,
          unsigned long long& lcm) {
  unsigned long long temp = t / lcm;
  if ((t - lcm * temp) < a) return true;
  return false;
}
bool OK(unsigned long long a, unsigned long long& b, unsigned long long& lcm) {
  a /= gcd(a, b);
  if (lcm / a == b) return true;
  return false;
}
int main() {
  unsigned long long t, a, b, Sum = 0, temp, temp1, temp2, temp3;
  cin >> t >> a >> b;
  if (a > b) {
    temp = a;
    a = b;
    b = temp;
  }
  temp2 = lcm(a, b);
  if (OK(a, b, temp2)) {
    temp1 = a - 1;
    temp3 = (t / temp2) * a;
    if (CALC(t, a, b, temp2)) {
      temp3 -= a;
      temp3 += t % temp2 + 1;
    }
    Sum += temp1 + temp3;
  } else
    Sum = a - 1;
  temp = gcd(Sum, t);
  Sum /= temp;
  t /= temp;
  if (Sum >= t)
    cout << "1/1" << endl;
  else
    cout << Sum << "/" << t << endl;
  return 0;
}
