#include<cstdio>
#include<cstring>
using namespace std;
int main(){
    char a[7][7] = {"","*abcde","*fghij","*klmno","*pqrst","*uvwxy","*z.?! "};

    while(~scanf("%s",s)){
        char s[200];
        if(strlen(s)%2==1)printf("NA\n");
        else{
            for(int i=0;i<strlen(s);i+=2){
                printf("%c",a[s[i]-48][s[i+1]-48]);

            }
            printf("\n");
        }
    }
    return 0;
}