Palindrome Sentence

Lab C Intermediate 20 points

Read a line and print YES if it is a palindrome ignoring case and non-letters, else NO.

Input

One line.

Output

YES or NO

Example

Input

A man, a plan, a canal: Panama

Output

YES

Sample input available Sample output available

Editor

Hints

Skip characters that aren't letters from both ends.

Solution explanation

Skipping inside the two-pointer loop avoids building a cleaned copy.

Show solution

#include <stdio.h>
#include <string.h>
#include <ctype.h>

int main() {
    char s[200];
    fgets(s, 200, stdin);
    int i = 0, j = strlen(s) - 1, ok = 1;
    while (i < j) {
        if (!isalpha(s[i])) { i++; continue; }
        if (!isalpha(s[j])) { j--; continue; }
        if (tolower(s[i]) != tolower(s[j])) { ok = 0; break; }
        i++;
        j--;
    }
    printf(ok ? "YES\n" : "NO\n");
    return 0;
}

Output

Answer