func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, k;     cin >> n >> k;     string s;     cin >> s;     int l = s.length();     int f[l + 2];     int a[26] = {0};     int l1[1000005], l2[1000005];     for (int i = 0; i <= l; i++) {       f[i] = 0, l1[i] = 0, l2[i] = 0;     }     for (int i = 0; i < 26; i++) a[i] = 0;     int flag = 0;     for (int i = 0; i < l; i++) {       if (a[s[i] -  A ] == 0) {         a[s[i] -  A ] = 1;         l1[i] = 1;       }     }     for (int i = 0; i < 26; i++) a[i] = 0;     for (int i = l - 1; i >= 0; i--) {       if (a[s[i] -  A ] == 0) {         a[s[i] -  A ] = 1;         l2[i + 1] = -1;       }     }     f[0] = l1[0];     for (int i = 1; i <= l; i++) {       f[i] = f[i - 1] + l1[i] + l2[i];     }     for (int i = 0; i <= l; i++) {       if (f[i] > k) {         flag = 1;         break;       }     }     if (flag == 1)       cout <<  YES ;     else       cout <<  NO ;     return 0;   }   