func_code_string: #include <bits/stdc++.h>   using namespace std;   void ioe() {     freopen( in_3.txt ,  r , stdin);     freopen( out_3.txt ,  w , stdout);     freopen( er_3.txt ,  w , stderr);   }   struct lex_compare {    public:     bool operator()(const pair<long long, long long>& lhs,                     const pair<long long, long long>& rhs) const {       return (lhs.second > rhs.second);     }   };   long long pw(long long a, long long b, long long m) {     if (b == 0) return 1;     long long t = (pw(a, b / 2, m)) % m;     t = (t * t) % m;     if (b % 2 == 0) return t;     return (a * t) % m;   }   long long gc(long long a, long long b) {     if (b == 0) return a;     return gc(b, a % b);   }   vector<string> splt(string x, char w) {     vector<string> v;     string s;     int l = x.length();     for (long long i = 0; i < l; i++) {       if (x[i] == w) {         v.push_back(s);         s =   ;       } else {         s.push_back(x[i]);       }     }     v.push_back(s);     return v;   }   class node {    public:     long long id, a, l;     vector<node*> v;     vector<pair<node*, long long>> vm;     node* prt = NULL;     long long s = -1, x = 0, y = 0;     node(long long x = 0, long long y = 0) {       id = y, a = x, l = 0;       vm.clear(), v.clear();       prt = NULL;       s = -1, x = 0, y = 0;     }     void adn(node* t) { v.push_back(t), l++; }     void adn(node* t, long long x) { vm.push_back({t, x}), l++; }   };   node* nnd(long long a = 0, long long i = 1) {     node* t = new node(a, i);     return t;   }   void solve() {     long long n;     cin >> n;     char a[n][n];     for (long long i = 0; i < n; i++)       for (long long j = 0; j < n; j++) cin >> a[i][j];     long long t = 0;     for (long long i = 0; i < n; i++)       for (long long j = 0; j < n; j++) {         long long x = 0;         if (i > 0 && a[i - 1][j] ==  o ) x++;         if (j > 0 && a[i][j - 1] ==  o ) x++;         if ((i < n - 1) && a[i + 1][j] ==  o ) x++;         if ((j < n - 1) && a[i][j + 1] ==  o ) x++;         if (x % 2 == 1) t++;       }     if (t == 0)       cout <<  YES n ;     else       cout <<  NO n ;   }   signed main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     ;     long long t = 1;     long long f = t;     while (f--) {       solve();     }   }   