/**

 * C语言合法标识符

 */

import java.util.*;

public class acm2024 {

public static void main(String[] args) {

Scanner in = new Scanner(System.in);

int n = in.nextInt();

in.nextLine();

while (n--!= 0) {

String str = in.nextLine();

char[] chs = str.toCharArray();

//Character.isLetter(chs[0])确定指定字符是否为字母

if (!(Character.isLetter(chs[0]) || chs[0] == '_')) {

System.out.println("no");

continue;

}

boolean flag = true;

for (int i = 1; i < chs.length; i++) {

//Character.isDigit(chs[i])确定指定字符是否为数字 Character.isLetter(chs[i])确定指定字符是否为字母

if (!(Character.isDigit(chs[i]) || Character.isLetter(chs[i]) || chs[i] == '_')) {

flag = false;

break;

}

}

if(flag)

System.out.println("yes");

else

System.out.println("no");

}

}

}