#include <stdio.h>

int main(void)
{

        unsigned int h,je, f, p[10000], i, h1, h2;

        scanf("%d %d",&h,&f);

        do {
        for (i=0;i<f;i++) p[i]=0;
        for (i=1;i<=h2;i++)
        {       scanf("%d %d",&h1,&h2);
                p[h1]++;
                p[h2]++;
        }
        je=1;
        for (i=1;i<=f;i++) if (p[i]>2) je=0;
        if (je) printf("Yes, village can be built");
          else printf("No, village cannot be built");

        } while ((h!=0)&&(f!=0));



        return 0;
}