func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long oo = 2e9, MOD = 998244353;   int dx[] = {1, 0, -1, 0, 1, 1, -1, -1};   int dy[] = {0, -1, 0, 1, 1, -1, 1, -1};   int main() {     int n, k;     string s;     cin >> n >> k >> s;     for (int i = 0; i < (int)s.size() - 1 && k; i++) {       if (s[i] ==  4  and s[i + 1] ==  7 ) {         if (((i + 1) & 1) and i + 2 < (int)s.size() and s[i + 2] ==  7 ) {           k %= 2;           if (k) {             s[i] =  4 , s[i + 1] =  4 ;           }           break;         }         if (!((i + 1) & 1) and i - 1 >= 0 and s[i - 1] ==  4 ) {           k %= 2;           if (k) {             s[i] =  7 , s[i + 1] =  7 ;           }           break;         }         if ((i + 1) & 1) {           s[i] =  4 , s[i + 1] =  4 ;         } else {           s[i] =  7 , s[i + 1] =  7 ;         }         k--;       }     }     cout << s;     return 0;   }   