#include <bits/stdc++.h>
long long int gcd(long long int x, long long int y) {
  if (y == 0)
    return x;
  else
    return gcd(y, x % y);
}
long long int lcm(long long int x, long long int y) {
  long long int a = x / gcd(x, y);
  return a * y;
}
int main(int argc, const char* argv[]) {
  long long int b, w, t;
  scanf("%lld", &t);
  scanf("%lld", &w);
  scanf("%lld", &b);
  long long int min = b > w ? w : b;
  long long int total = t > min - 1 ? min - 1 : t;
  if (total == t) {
    printf("1/1");
    return 0;
  }
  long long int lcmt = lcm(b, w);
  int upps = 0;
  if (lcmt < 0)
    upps = 1;
  else {
    if (lcmt / b * b != lcmt)
      upps = 1;
    else if (lcmt / w * w != lcmt)
      upps = 1;
  }
  if (!upps) {
    long long int tdlcm = t / lcmt;
    total = (total + 1) * tdlcm;
    total += t - tdlcm * lcmt > min - 1 ? min - 1 : t - tdlcm * lcmt;
  } else {
    total = 0;
    total += t > min - 1 ? min - 1 : t;
  }
  long long int g = gcd(total, t);
  printf("%lld/%lld", total / g, t / g);
  return 0;
}
