int main(){
    int n,i,j;
    int sum[100]={0};
    char str[21][21];
    scanf("%d\n",&n);
    for(i=0;i<n;i++){
        gets(str[i]);
        for(j=0;str[i][j]!='\0';j++){
            if(j==0){
                if((str[i][j]>='A'&&str[i][j]<='Z')||(str[i][j]>='a'&&str[i][j]<='z')||(str[i][j]=='_')){
                    sum[i]=1;
                }
                else{
                    sum[i]=0;
                    break;
                }
            }
            else if(j>0){
                if((str[i][j]>='A'&&str[i][j]<='Z')||(str[i][j]>='a'&&str[i][j]<='z')||(str[i][j]=='_')||(str[i][j]>='0'&&str[i][j]<='9')){
                    sum[i]=1;
                }
                else{
                    sum[i]=0;
                    break;
                }
            }
            else{
                sum[i]=0;
                break;
            }
        }
        if(sum[i]==0){
            printf("no\n");
        }
        else{
            printf("yes\n");
        }
    }
    return 0;
}