Problem p02723 (C++)

Buggy submission (status: Runtime Error):
#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define FAST ios_base::sync_with_stdio(false);
#define FO cout.tie(NULL);
#define FI cin.tie(NULL);
#define IN cin >>
#define OUT cout <<
#define loop(i, a, n) for (int i = a; i < n; i++)
#define rloop(i, a, n) for (int i = a; i >= n; i--)
#define endl "\n";
#define pb push_back
#define mp make_pair
#define set_bits(a) __builtin_popcountll(a)
#define ll long long int
#define ld long double
#define vll vector<long long int>
#define pll pair<long long int, long long int>
#define mod 1000000007
#define M 998244353
ll gcd(ll a, ll b) { return (b ? gcd(b, a % b) : a); }
ll P(ll B, ll power, ll modulo) {
  ll ans = 1LL;
  while (power > 0LL) {
    if (power % 2LL == 1LL) {
      ans = (ans * B) % modulo;
    }
    B = (B * B) % modulo;
    power /= 2LL;
  }
  return ans;
}
bool isPrime(ll n) {
  if (n <= 1LL) {
    return false;
  }
  if (n <= 3LL) {
    return true;
  }
  if (n % 2 == 0LL || n % 3 == 0LL) {
    return false;
  }
  for (ll i = 5LL; (i * i) <= n; i += 6LL) {
    if (n % i == 0LL || n % (i + 2LL) == 0LL) {
      return false;
    }
  }
  return true;
}
using namespace std;
bool sortbysec(const pair<int, int> &a, const pair<int, int> &b) {
  return (a.second < b.second);
}
bool sortbysecll(const pll &a, const pll &b) { return (a.second < b.second); }
ll modinv(ll x, ll y, ll modulo) {
  return ((x % modulo) * (P(y, modulo - 2LL, modulo) % modulo)) % modulo;
}
void vok() {
  FAST FO FI
#ifndef ONLINE_JUDGE
      freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
}
const int mxN = 200010;
int t[mxN], ans[mxN];
int main() {
  vok();
  string s;
  IN s;
  if (s[2] == s[3] && s[4] == s[5]) {
    OUT "Yes" << endl
  } else {
    OUT "No" << endl
  }
  return 0;
}

Fixed submission:
#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define FAST ios_base::sync_with_stdio(false);
#define FO cout.tie(NULL);
#define FI cin.tie(NULL);
#define IN cin >>
#define OUT cout <<
#define loop(i, a, n) for (int i = a; i < n; i++)
#define rloop(i, a, n) for (int i = a; i >= n; i--)
#define endl "\n";
#define pb push_back
#define mp make_pair
#define set_bits(a) __builtin_popcountll(a)
#define ll long long int
#define ld long double
#define vll vector<long long int>
#define pll pair<long long int, long long int>
#define mod 1000000007
#define M 998244353
ll gcd(ll a, ll b) { return (b ? gcd(b, a % b) : a); }
ll P(ll B, ll power, ll modulo) {
  ll ans = 1LL;
  while (power > 0LL) {
    if (power % 2LL == 1LL) {
      ans = (ans * B) % modulo;
    }
    B = (B * B) % modulo;
    power /= 2LL;
  }
  return ans;
}
bool isPrime(ll n) {
  if (n <= 1LL) {
    return false;
  }
  if (n <= 3LL) {
    return true;
  }
  if (n % 2 == 0LL || n % 3 == 0LL) {
    return false;
  }
  for (ll i = 5LL; (i * i) <= n; i += 6LL) {
    if (n % i == 0LL || n % (i + 2LL) == 0LL) {
      return false;
    }
  }
  return true;
}
using namespace std;
bool sortbysec(const pair<int, int> &a, const pair<int, int> &b) {
  return (a.second < b.second);
}
bool sortbysecll(const pll &a, const pll &b) { return (a.second < b.second); }
ll modinv(ll x, ll y, ll modulo) {
  return ((x % modulo) * (P(y, modulo - 2LL, modulo) % modulo)) % modulo;
}
void vok() {
  FAST FO FI
#ifndef ONLINE_JUDGE
      freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
}
const int mxN = 200010;
int t[mxN], ans[mxN];
int main() {
  // vok();
  string s;
  IN s;
  if (s[2] == s[3] && s[4] == s[5]) {
    OUT "Yes" << endl
  } else {
    OUT "No" << endl
  }
  return 0;
}