#include <bits/stdc++.h>
using namespace std;
long long Min(long long a, long long b) { return (a < b) ? a : b; }
long long GCD(long long a, long long b) { return (b == 0) ? a : GCD(b, a % b); }
int main() {
  long long t, a, b;
  scanf("%I64d%I64d%I64d", &t, &a, &b);
  if (a == b) {
    printf("1/1");
    return 0;
  }
  long long res, tmp;
  if (a > (t / b) && GCD(a, b) == 1) {
    res = Min(a, b) - 1;
    if (res > t) res = t;
    tmp = GCD(res, t);
    printf("%I64d/%I64d", res / tmp, t / tmp);
    return 0;
  }
  if (a / GCD(a, b) > t / b) {
    res = Min(a, b) - 1;
    if (res > t) res = t;
    tmp = GCD(res, t);
    printf("%I64d/%I64d", res / tmp, t / tmp);
    return 0;
  }
  tmp = a / GCD(a, b) * b;
  long long vmin = tmp, vmax = Min(vmin + a - 1, vmin + b - 1),
            times = t / vmin;
  if (vmin * times + Min(a, b) - 1 <= t)
    res = (vmax - vmin + 1) * times;
  else
    res = (vmax - vmin + 1) * (times - 1) + (t - (vmin * times) + 1);
  res += Min(a, b) - 1;
  tmp = GCD(res, t);
  printf("%I64d/%I64d", res / tmp, t / tmp);
  return 0;
}
