Challenge: Palindrome

Lab C++ Intermediate 20 points

A palindrome reads the same forwards and backwards, like level or racecar. Read one word (small letters only) and print yes if it is a palindrome, otherwise no.

Input

One word.

Output

yes or no.

Example

Input

racecar

Output

yes

Sample input available Sample output available

Editor

C++

Hints

Compare the first letter with the last, the second with the second-to-last, and so on.

The partner of index i is n - 1 - i.

Another way: copy the word, reverse the copy, and compare.

Solution explanation

Walk from both ends towards the middle. One mismatch is enough to say no.

Show solution

#include <iostream>
#include <string>
using namespace std;

int main() {
    string word;
    cin >> word;
    bool same = true;
    int n = word.length();
    for (int i = 0; i < n / 2; i++) {
        if (word[i] != word[n - 1 - i]) {
            same = false;
        }
    }
    cout << (same ? "yes" : "no") << "\n";
    return 0;
}

Output

Answer