#include<bits/stdc++.h>
using namespace std;
#define maxn 123456
int n,head[maxn],deep[maxn],power[maxn];
int cnt,ans,x,y,k,dp[maxn][50],lcaaaaa;
struct edg
{
    int v,to;
} edge[maxn];
void adda(int x,int y)
{
    edge[++cnt].to=head[x];
    edge[cnt].v=y;
    head[x]=cnt;
}
void dfs(int cur,int fa)
{
    deep[cur]=deep[fa]+1;
    dp[cur][0]=fa;
    for(int i=1; (1<<i)<=deep[cur]; i++)
        dp[cur][i]=dp[dp[cur][i-1]][i-1];
    for(int i=head[cur]; i!=-1; i=edge[i].to)
        if(edge[i].v!=fa)
            dfs(edge[i].v,cur);
}
int lca(int x,int y)
{
    if(deep[x]<deep[y])
        swap(x,y);
    for(int i=30; i>=0; i--)
        if(deep[x]-(1<<i)>=deep[y])
            x=dp[x][i];
    if(x==y)return x;
    for(int i=30; i>=0; i--)
        if(dp[x][i]!=dp[y][i])
        {
            x=dp[x][i];
            y=dp[y][i];
        }
    return dp[x][0];
}
void get(int cur,int fa)
{
    for(int i=head[cur]; i!=-1; i=edge[i].to)
    {
        if(edge[i].v==fa)continue;
        get(edge[i].v,cur);
        power[cur]+=power[edge[i].v];
    }
    ans=max(ans,power[cur]);
}
int main()
{
    memset(head,-1,sizeof(head));
    scanf("%d%d",&n,&k);
    for(int i=1; i<n; i++)
    {
        scanf("%d%d",&x,&y);
        adda(x,y);
        adda(y,x);
    }
    deep[0]=0;
    dfs(1,0);
    while(k--)
    {
        scanf("%d%d",&x,&y);
        lcaaaaa=lca(x,y);
        power[x]++;
        power[y]++;
        power[lcaaaaa]--;
        power[dp[lcaaaaa][0]]--;
    }
    get(1,0);
    printf("%d\n",ans);
    return 0;
}