#include<cstdio>
#include<cstring>
using namespace std;

int main(void)
{
	char buf[201],b[101];
	int i,a,flg;
	char moji[5][6]={{'a','f','k','p','u','z'},
					{'b','g','l','q','v','.'},
					{'c','h','m','r','w','?'},
					{'d','i','n','s','x','!'},
					{'e','j','o','t','y',' '}};
	int len;
	int su1,su2;

	while(scanf("%s",buf)!=EOF)	{
		flg=1;
		len=strlen(buf);
		if(len%2==1)	flg=0;
		else {
			for(i=0;i<len/2;i++)	{
				su1=buf[i*2]-'0';
				su2=buf[i*2+1]-'0';
				if(su1<=0 || su1>6 || su2<=0 || su2>5)	{
					flg=0;
					break;
				}
//				printf("su2=%d su2=%d\n",su2,su1);
				b[i]=moji[su2-1][su1-1];
			}
			b[len/2]='\0';
		}
		if(flg==1)	{
			printf("%s\n",b);
		}
		else {
			printf("NA\n");
		}
	}
	return 0;
}
