#include <cstdio>
#define DN 100002

int grad[DN];

int main()
{
	freopen("colorare3.in","r",stdin);
	freopen("colorare3.out","w",stdout);
	int n,k,gm=0,x,y;
	scanf("%d %d",&n,&k);
	for(int i=1; i<n; i++) {
		scanf("%d %d",&x,&y);
		++grad[x];
		if(grad[x]>gm) gm=grad[x];
		++grad[y];
		if(grad[y]>gm) gm=grad[y];
	}
	if(k<gm+1) printf("0\n");
	if(k==gm) printf("k");
}