#include<iostream>
#include<cstring>
#include<cstdio>using namespace std;inline int rd(){int ret=0,f=1;char c;while(c=getchar(),!isdigit(c))f=c=='-'?-1:1;while(isdigit(c))ret=ret*10+c-'0',c=getchar();return ret*f;
}const int MAXN=500005<<2;struct Edge{int next,to;Edge(int x=0,int y=0){next=x;to=y;}
}e[MAXN];
int ecnt,head[MAXN];
inline void add(int x,int y){e[++ecnt]=Edge(head[x],y);head[x]=ecnt;
}int n,m;int fa[MAXN],dep[MAXN],siz[MAXN],hs[MAXN];
void dfs1(int x,int pre){fa[x]=pre;dep[x]=dep[pre]+1;siz[x]=1;int mx=0,tmp=0;for(int i=head[x];i;i=e[i].next){int v=e[i].to;if(v==pre) continue;dfs1(v,x);siz[x]+=siz[v];if(siz[v]>mx){mx=siz[v];tmp=v;}}hs[x]=tmp;
}int top[MAXN],id[MAXN],tot;
void dfs2(int x,int tp){top[x]=tp;id[x]=++tot;if(hs[x]) dfs2(hs[x],tp);for(int i=head[x];i;i=e[i].next){int v=e[i].to;if(v==fa[x]||v==hs[x]) continue;dfs2(v,v);}
}int lca(int x,int y){int ret;while(top[x]!=top[y]){dep[top[x]]>dep[top[y]]?x=fa[top[x]]:y=fa[top[y]];}return dep[x]<dep[y]?x:y;
}int ans,sum[MAXN];
void dfs(int cur){for(int i=head[cur];i;i=e[i].next){int v=e[i].to;if(v==fa[cur]) continue;dfs(v);sum[cur]+=sum[v];}ans=max(sum[cur],ans);
}int main(){n=rd();m=rd();int x,y,t;for(int i=1;i<=n-1;i++){x=rd();y=rd();add(x,y);add(y,x);}dfs1(1,0);dfs2(1,1);for(int i=1;i<=m;i++){x=rd();y=rd();t=lca(x,y);sum[x]+=1;sum[y]+=1;sum[t]-=1;sum[fa[t]]-=1;}dfs(1);cout<<ans<<endl;return 0;
}

#include<iostream>
#include<cstring>
#include<cstdio>using namespace std;inline int rd(){int ret=0,f=1;char c;while(c=getchar(),!isdigit(c))f=c=='-'?-1:1;while(isdigit(c))ret=ret*10+c-'0',c=getchar();return ret*f;
}const int MAXN=500005<<2;struct Edge{int next,to;Edge(int x=0,int y=0){next=x;to=y;}
}e[MAXN];
int ecnt,head[MAXN];
inline void add(int x,int y){e[++ecnt]=Edge(head[x],y);head[x]=ecnt;
}int n,m;struct Seg{#define ls (cur<<1)#define rs (cur<<1|1)#define mid (l+r>>1)int mx[MAXN],add[MAXN];Seg(){memset(mx,0,sizeof(mx));memset(add,0,sizeof(add));}void pushup(int cur){mx[cur]=max(mx[ls],mx[rs]);}void pushdown(int cur,int l,int r){int v=add[cur];add[ls]+=v;add[rs]+=v;mx[ls]+=v;mx[rs]+=v;add[cur]=0;}void build(int cur,int l,int r){if(l==r) {mx[cur]=0;return;}build(ls,l,mid);build(rs,mid+1,r);pushup(cur);}void update(int L,int R,int cur,int l,int r,int w){if(L<=l&&r<=R){mx[cur]+=w;add[cur]+=w;return;}pushdown(cur,l,r);if(L<=mid) update(L,R,ls,l,mid,w);if(mid <R) update(L,R,rs,mid+1,r,w);pushup(cur);}
}T;int fa[MAXN],dep[MAXN],siz[MAXN],hs[MAXN];
void dfs1(int x,int pre){fa[x]=pre;dep[x]=dep[pre]+1;siz[x]=1;int mx=0,tmp=0;for(int i=head[x];i;i=e[i].next){int v=e[i].to;if(v==pre) continue;dfs1(v,x);siz[x]+=siz[v];if(siz[v]>mx){mx=siz[v];tmp=v;}}hs[x]=tmp;
}int top[MAXN],id[MAXN],tot;
void dfs2(int x,int tp){top[x]=tp;id[x]=++tot;if(hs[x]) dfs2(hs[x],tp);for(int i=head[x];i;i=e[i].next){int v=e[i].to;if(v==fa[x]||v==hs[x]) continue;dfs2(v,v);}
}void updateLink(int x,int y,int w){while(top[x]!=top[y]){if(dep[top[x]]<dep[top[y]]) swap(x,y);T.update(id[top[x]],id[x],1,1,n,w);x=fa[top[x]];}if(dep[x]>dep[y]) swap(x,y);T.update(id[x],id[y],1,1,n,w);
}int main(){n=rd();m=rd();int x,y;for(int i=1;i<=n-1;i++){x=rd();y=rd();add(x,y);add(y,x);}dfs1(1,0);dfs2(1,1);T.build(1,1,n); for(int i=1;i<=m;i++){x=rd();y=rd();updateLink(x,y,1);}cout<<T.mx[1];return 0;
}