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#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<queue>
#include<map>
#include<stack>
#include<cmath>
#include<set>
#include<bitset>
#include<assert.h>
#define inc(i,l,r) for(int i=l;i<=r;i++)
#define dec(i,l,r) for(int i=l;i>=r;i--)
#define link(x) for(edge *j=h[x];j;j=j->next)
#define mem(a) memset(a,0,sizeof(a))
#define ll long long
#define eps 1e-8
#define succ(x) (1<<x)
#define lowbit(x) (x&(-x))
#define sqr(x) ((x)*(x))
#define mid (x+y)/2
#define NM 100005
#define nm 200005
#define pi 3.1415926535897931
using namespace std;
const int inf=1e9+7;
ll read(){
ll x=0,f=1;char ch=getchar();
while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
while(isdigit(ch))x=x*10+ch-'0',ch=getchar();
return f*x;
}
struct edge{int t;edge*next;}e[nm],*h[NM],*o=e;
void add(int x,int y){o->t=y;o->next=h[x];h[x]=o++;}
int d[NM],top[NM],son[NM],end[NM],TOP,tot,id[NM],f[NM],size[NM],c[NM];
int dp[NM][2],g[NM][2],n,m,a[NM],_x,_y;
void dfs1(int x){
size[x]=1;dp[x][1]=a[x];dp[x][0]=0;
link(x)if(j->t!=f[x]){
f[j->t]=x;d[j->t]=d[x]+1;
dfs1(j->t);
dp[x][1]+=dp[j->t][0];
dp[x][0]+=max(dp[j->t][1],dp[j->t][0]);
if(size[j->t]>size[son[x]])son[x]=j->t;
size[x]+=size[j->t];
}
}
int dfs2(int x){
top[x]=TOP;id[x]=++tot;end[x]=x;c[tot]=x;
if(son[x])end[x]=dfs2(son[x]);
g[x][1]=a[x];g[x][0]=0;
link(x)if(!top[j->t]){
dfs2(TOP=j->t);
g[x][1]+=dp[j->t][0];
g[x][0]+=max(dp[j->t][1],dp[j->t][0]);
}
return end[x];
}
struct mat{int n,m,a[2][2];}one;
mat operator*(const mat&x,const mat&y){
mat s;s.n=x.n;s.m=y.m;mem(s.a);
inc(i,0,x.n)inc(k,0,x.m)inc(j,0,s.m)s.a[i][j]=max(s.a[i][j],x.a[i][k]+y.a[k][j]);
return s;
}
struct node{
node*l,*r;
int x,y;
mat s;
node(int x,int y,node*l=0,node*r=0):x(x),y(y),l(l),r(r){
if(x==y){
s.n=s.m=1;s.a[0][0]=s.a[0][1]=g[c[x]][0];s.a[1][0]=g[c[x]][1];s.a[1][1]=-inf;
}else upd();
}
void upd(){s=l->s*r->s;}
void mod(){
if(x==y){
s.a[0][0]=s.a[0][1]=g[c[x]][0];s.a[1][0]=g[c[x]][1];
return;
}
if(_x<=mid)l->mod();else r->mod();
upd();
}
mat sum(){
if(_x<=x&&y<=_y)return s;
if(_x>mid)return r->sum();
if(_y<=mid)return l->sum();
return l->sum()*r->sum();
}
}*root;
node*build(int x,int y){return x==y?new node(x,y):new node(x,y,build(x,mid),build(mid+1,y));}
void ch(int x){
g[x][1]+=_y-a[x];a[x]=_y;
_x=id[x];root->mod();
while(top[x]>1){
x=top[x];
_x=id[x];_y=id[end[x]];mat t=root->sum()*one;
g[f[x]][1]+=t.a[0][0]-dp[x][0];
g[f[x]][0]+=max(t.a[0][0],t.a[1][0])-max(dp[x][0],dp[x][1]);
dp[x][1]=t.a[1][0];dp[x][0]=t.a[0][0];
x=f[top[x]];_x=id[x];root->mod();
}
}
int main(){
n=read();m=read();
inc(i,1,n)a[i]=read();
inc(i,2,n){_x=read();_y=read();add(_x,_y);add(_y,_x);}
dfs1(f[1]=1);dfs2(TOP=1);
root=build(1,n);
one.n=1;one.m=0;
_x=1;_y=id[end[1]];mat ans=root->sum()*one;
while(m--){
_x=read();_y=read();ch(_x);
_x=1;_y=id[end[1]];mat ans=root->sum()*one;
printf("%d\n",max(ans.a[0][0],ans.a[1][0]));
}
return 0;
}
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