#include <cstdio>
#include <cctype>
#include <string>
#include <algorithm>

bool P(std::string s,int &len){
    
    std::string str = "";
    
    for (int i = 0;i < s.length();i++) 
        if (isalpha(s[i]))
            str += toupper(s[i]);
    len = str.length();
    for (int i = 0,j = str.length() - 1;i < j;i++,j--)
        if (str[i] != str[j])
            return 0;
    
    return 1;
}

int main(){
    
    char s[20005];
    int len,anslen = 0;
    std::string str,str2,ans = "";
    
    scanf("Confucius say: ");
    fread(s,1,20005,stdin);
    str = s;
    for (int i = 0;i < str.length();i++)
        for (int j = i + 1;j < std::min(2500,(int)str.length());j++){
            
            str2 = str.substr(i,j - i);
            if (P(str2,len) && len > anslen) 
                ans = str2,anslen = len;
            
        }
    printf("%d\n%s\n",anslen,ans.c_str());
    
    return 0;
}

标签不就是枚举么，为啥会T这么多（#1#2#4AC，其他全T）