Palindrome

#include <iostream>
#include <string>
int main(){
    std::string str;
    std::cin>>str;
    int len = str.length();
    bool flag = true;
    for (int i = 0 ; i < len/2; i++){
        if (str[i] != str[len-i-1])
         flag = false;
    }
    
    std::cout<< (flag ? "YES" : "NO");
}