#include<bits/stdc++.h>
const int maxn=300;
inline const void read(int &a)
{
    a=0;
    char c=getchar();
    while(c<'0'||c>'9')c=getchar();
    while(c>='0'&&c<='9')
    {
        a=(a<<1)+(a<<3)+c-'0';
        c=getchar();
    }
}
inline const void write(int a)
{
    if(a>=10)write(a/10);
    putchar(a%10+'0');
}
int d=0,n,dis[maxn],step,point[maxn],to[maxn],next[maxn],big=-1;
bool been[maxn];
inline const void add(int a,int b)
{
    next[++d]=point[a];
    to[d]=b;
    point[a]=d;
}
const void dfs(int p)
{
    big=std::max(big,dis[p]);
    been[p]=true;
    int side=point[p];
    while(side>=0)
    {
        if(!been[to[side]]){dis[to[side]]=dis[p]+1;dfs(to[side]);}
        side=next[side];
    }
}
int main()
{
    memset(been,false,sizeof(been));
    memset(dis,0,sizeof(dis));
    memset(point,-1,sizeof(point));
    read(n);read(step);step++;
    int x,y;
    for(int i=1;i<=n-1;i++)
    {read(x);read(y);add(x,y);add(y,x);}
    dis[0]=1;
    dfs(0);
    if(step<=big)write(step);
    else
    {
        int rest=(step-big)/2,ans=rest+big;
        write(ans);
    }
    return 0;
}