poj 3417

#include 
#include 
using namespace std;
typedef long long LL;
const int maxn = 100005;
const int maxm = 200005;
int he[maxn],ver[maxm],tot,ne[maxm],fa[maxn][21],d[maxn],v[maxn];
void add( int x,int y ){
    ver[++tot] = y;
    ne[tot] = he[x];
    he[x] = tot;
}
void dfs( int x,int f ){
    for( int i = 1;i <= 20;i++ ){
        fa[x][i] = fa[ fa[x][i-1] ][i-1];
    }
    for( int cure = he[x];cure;cure = ne[cure] ){
        int y = ver[cure];
        if( y == f ) continue;
        fa[y][0] = x;
        d[y] = d[x]+1;
        dfs(y,x);
    }
}
int lca( int x,int y ){
    if( d[x] < d[y] ) swap(x,y);
    for( int i = 20;i >= 0;i-- ){
        if( d[ fa[x][i] ] >= d[y] ){
            x = fa[x][i];
        }
    }
    if( x==y ) return x;
    for( int i = 20;i >= 0;i-- ){
        if( fa[x][i] == fa[y][i] ) continue;
        x = fa[x][i];y =fa[y][i];
    }
    return fa[x][0];
}
void dfs2( int x,int f ){
    for( int cure = he[x];cure;cure = ne[cure] ){
        int y = ver[cure];
        if( y == f ) continue;
        dfs2(y,x);
        v[x] += v[y];
    }
}
int main(){
    int n,m;
    scanf("%d%d",&n,&m);
    for( int x,y,i = 1;i <= n-1;i++ ){
        scanf("%d%d",&x,&y);
        add(x,y);add(y,x);
    }
    dfs(1,0);
    for( int x,y,i = 1;i <= m;i++ ){
        scanf("%d%d",&x,&y);
        int z = lca(x,y);
        v[x]++;v[y]++;v[z]-=2;
    }
    dfs2(1,0);
    LL ans = 0;
    for( int i = 2;i <= n;i++ ){
        if( v[i] == 1 ){
            ans++;
        }else if( v[i] == 0 ){
            ans += m;
        }
    }
    printf("%lld\n",ans);
    return 0;
}