杭电2024

#include<stdio.h>
char s[51];
int lenth(char s[])
{
    int i=0;
    while(s[i])
        ++i;
    return i;
}
int main()
{
    int i,n;
    while(~scanf("%d",&n))
    {
        getchar();
        while(n--)
        {
            gets(s);
            int len=lenth(s);
            for(i=0; i<len; ++i)
            {
                if(i)
                {
                    if(!(s[i]=='_'||(s[i]>='a'&&s[i]<='z')||(s[i]>='A'&&s[i]<='Z')||(s[i]>='0'&&s[i]<='9')))
                        break;
                }
                else
                    if(!( s[i]=='_' || (s[i]>='a'&&s[i]<='z') || (s[i]>='A'&&s[i]<='Z') ))
                        break;
            }
            if(i==len)
                printf("yes
");
            else
                printf("no
");
        }
    }
    return 0;
}