Uva 401 palindrom

#include<stdio.h>
#include<string.h>
#include<ctype.h>
const char* rev = "A   3  HIL JM O   2TUVWXY51SE Z  8 ";
const char *msg[] = {"not a palindrome", "a regular palindrome", "a mirrored string", "a mirrored palindrome"};
char r(char ch)
{
    if(isalpha(ch)) return rev[ch - 'A'];
    return rev[ch - '0' + 25];
}
int main()
{
    char s[30];
    while(scanf("%s", s)==1)
    {
        int len = strlen(s);
        int p = 1, m = 1;
        for(int i = 0; i < (len+1)/2; i++)
        {
            if(s[i] != s[len-1-i]) p = 0;
            if(r(s[i]) != s[len-1-i]) m = 0;
        }
        printf("%s -- is %s.\n\n", s, msg[m*2+p]);
    }
    return 0;
}