Problem p02687 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
using namespace std;

#define fast()                                                                 \\
  ios::sync_with_stdio(0);                                                     \\
  cin.tie(0);                                                                  \\
  cout.tie(0);
#define ll long long int
#define test()                                                                 \\
  ll t;                                                                        \\
  cin >> t;                                                                    \\
  while (t--)
#define lp0(i, begin, end) for (ll i = begin; i < end; i++)
#define lp1(i, begin, end) for (ll i = begin; i <= end; i++)
#define rlp(i, begin, end) for (ll i = end; i >= begin; i--)
#define prec(n) fixed << setprecision(n)
#define initial(a, i) memset(a, i, sizeof(a))
#define pb push_back
#define PI 3.1415926535897932384626433832795
#define MOD 1000000007
#define F first
#define S second
#define all(a) (a).begin(), (a).end()
#define BPC(x) __builtin_popcountll(x)
#define gcd(a, b) __gcd(a, b)

ll gcd(ll a, ll b) {
  if (a == 0)
    return b;
  return gcd(b % a, a);
}

ll power(ll x, ll n) {
  ll result = 1;
  while (n) {
    if (n & 1)
      result = result * x;
    n = n / 2;
    x = x * x;
  }
  return result;
}

// Solution Function
void solution(ll compte) {
  // cout<<compte<<"\\n";
  string s;
  cin >> s;
  if (s == "ABC")
    puts("ARC");
  else
    puts("ABC");
}
// Driver Function
int main() {
  ll compte = 1;
  // test()
  //{
  solution(compte);
  compte++;
  //}
  return 0;
}


Error: WA

Fixed submission:

#include <bits/stdc++.h>
using namespace std;

#define fast()                                                                 \\
  ios::sync_with_stdio(0);                                                     \\
  cin.tie(0);                                                                  \\
  cout.tie(0);
#define ll long long int
#define test()                                                                 \\
  ll t;                                                                        \\
  cin >> t;                                                                    \\
  while (t--)
#define lp0(i, begin, end) for (ll i = begin; i < end; i++)
#define lp1(i, begin, end) for (ll i = begin; i <= end; i++)
#define rlp(i, begin, end) for (ll i = end; i >= begin; i--)
#define prec(n) fixed << setprecision(n)
#define initial(a, i) memset(a, i, sizeof(a))
#define pb push_back
#define PI 3.1415926535897932384626433832795
#define MOD 1000000007
#define F first
#define S second
#define all(a) (a).begin(), (a).end()
#define BPC(x) __builtin_popcountll(x)
#define gcd(a, b) __gcd(a, b)

ll gcd(ll a, ll b) {
  if (a == 0)
    return b;
  return gcd(b % a, a);
}

ll power(ll x, ll n) {
  ll result = 1;
  while (n) {
    if (n & 1)
      result = result * x;
    n = n / 2;
    x = x * x;
  }
  return result;
}

// Solution Function
void solution(ll compte) {
  // cout<<compte<<"\\n";
  ll k;
  cin >> k;
  ll s, w;
  cin >> s >> w;
  for (ll i = s; i < w + 1; i++) {
    if (i % k == 0) {
      puts("OK");
      return;
    }
  }
  cout << "NG\\n";
}
// Driver Function
int main() {
  ll compte = 1;
  // test()
  //{
  solution(compte);
  compte++;
  //}
  return 0;
}