#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxv 50050
#define maxe 100500
using namespace std;
struct edge
{
    int v,nxt;
}e[maxe];
int n,k,x,y,val[maxv],anc[maxv][20],ans=0,dis[maxv],g[maxv],nume=0;
void addedge(int u,int v)
{
    e[++nume].v=v;
    e[nume].nxt=g[u];
    g[u]=nume;
}
void dfs1(int x)
{
    for (int i=g[x];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if (v!=anc[x][0])
        {
            anc[v][0]=x;dis[v]=dis[x]+1;
            dfs1(v);
        }
    }
}
void get_table()
{
    for (int e=1;e<=19;e++)
        for (int i=1;i<=n;i++)
            anc[i][e]=anc[anc[i][e-1]][e-1];
}
int lca(int x,int y)
{
     if (dis[x]<dis[y]) swap(x,y);
     for (int e=19;e>=0;e--)
     {
         if ((dis[anc[x][e]]>=dis[y]) && (anc[x][e]))
            x=anc[x][e];
     }
     if (x==y) return x;
     for (int e=19;e>=0;e--)
     {
         if (anc[x][e]!=anc[y][e])
         {
             x=anc[x][e];
             y=anc[y][e];
         }
     }
     return anc[x][0];
}
void dfs2(int x)
{
    for (int i=g[x];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if (v!=anc[x][0])
        {
           dfs2(v);
           val[x]+=val[v];
        }
    }
    ans=max(ans,val[x]);
}
int main()
{
     scanf("%d%d",&n,&k);
    for (int i=1;i<=n-1;i++)
    {
        scanf("%d%d",&x,&y);
        addedge(x,y);addedge(y,x);
    }
    dfs1(1);get_table();
    for (int i=1;i<=k;i++)
    {
        scanf("%d%d",&x,&y);
        int t=lca(x,y);
        val[x]++;val[y]++;val[t]--;val[anc[t][0]]--;
    }
    dfs2(1);
    printf("%d\n",ans);
    return 0;
}