#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
int palindrom(char* string)
{
    size_t len = strlen(string);

    // handle empty string and string of length 1:
    if (len == 0) return 0;
    if (len == 1) return 1;

    char *ptr1 = string;
    char *ptr2 = string + len - 1;
    while(ptr2 >= ptr1) {
        if (!isalpha(*ptr2)) {
            ptr2--;
            continue;
        }
        if (!isalpha(*ptr1)) {
            ptr1++;
            continue;
        }
        if( tolower(*ptr1) != tolower(*ptr2)) {
            return 0;
        }
        ptr1++; ptr2--;
    }
    return 1;
}
int main()
{
    char c[80];
    int n;

    scanf("%d",&n);
    int i;
    for(i=0;i<80;i++){
        scanf("%c",&c[i]);
    }
    int j;
    for(i=0;i<80-n;i++){
        int tocno=1;
        char s[n-1];
        int counter=0;
        for(j=i;j<i+n;j++){
            s[counter]=c[j];
            counter++;
        }
        if(palindrom(s)){
            printf("%s\n",s);
        }else
            printf("NE\n");
    }
    return 0;
}