#include <bits/stdc++.h>
using namespace std;
#define maxn 50010
#define ll long long
#define res register int
struct Node {
    int to,next;
};
Node edge[maxn<<2]; //链式前向星要多开几倍数组
int head[maxn<<2],power[maxn],n,m,d[maxn],fa[maxn][30],ans,num;

inline int read() { //快读
    int s=0;
    char c=getchar();
    while (c<'0' || c>'9') c=getchar();
    while (c>='0' && c<='9') s=s*10+c-'0',c=getchar();
    return s;
}
//链式前向星
inline void add(int x,int y) {
    edge[++num].to=y,edge[num].next=head[x],head[x]=num;
}
//接下来是初始化
inline void work(int u,int fath) {
    d[u]=d[fath]+1,fa[u][0]=fath;
    for (res i=0; fa[u][i]; ++i)
        fa[u][i+1]=fa[fa[u][i]][i];
    for (res i=head[u]; i; i=edge[i].next) {
        int e=edge[i].to;
        if (e!=fath) work(e,u);
    }
}
//倍增求LCA
inline int Lca(int u,int v) {
    if (d[u]>d[v]) swap(u,v);
    for (res i=20; i>=0; --i) if (d[u]<=d[v]-(1<<i)) v=fa[v][i];
    if (u==v) return u;
    for (res i=20; i>=0; --i) if (fa[u][i]!=fa[v][i]) u=fa[u][i],v=fa[v][i];
    return fa[u][0];
}
//累计
inline void Get(int u,int fath) {
    for (res i=head[u]; i; i=edge[i].next) {
        int e=edge[i].to;
        if (e==fath) continue;
        Get(e,u);
        power[u]+=power[e];
    }
    ans=max(ans,power[u]);
}

int main() {
    n=read(),m=read();
    int x,y;
    for (res i=1; i<n; ++i) {
        x=read(),y=read();
        add(x,y);
        add(y,x);
    }
    work(1,0);
    for (res i=1; i<=m; ++i) {
        x=read(),y=read();
        int lca=Lca(x,y);
        ++power[x];
        ++power[y];
        --power[lca];
        --power[fa[lca][0]]; //树上差分
    }
    Get(1,0);
    printf("%d\n",ans);
    return 0;
}