题解 100% AC

#include <bits/stdc++.h>
using namespace std;
int main(){
    string a;
    int m,cnt=0;
    cin>>a>>m;
    for(int i=0;i<a.length();i++)if(a[i]>='A'&&a[i]<='Z') a[i]+=32;
    for(int i=0,j=a.length()-1;i<=a.length()/2;i++,j--){
        if(a[i]!=a[j]){
            cnt++;
        }
    }
    if(cnt<=m)cout<<"YES";
    else cout<<"NO";
	return 0;
}