RE且洛谷IDE运行有问题，但本机，牛客，JSOJ均可正确运行

#include <bits/stdc++.h>
using namespace std;
int Read();
void add_edge(int u,int v,int w);
int n,m,q;
struct pre_edge{
	int to,from;
	int w;
}pre_e[300005];
struct Edge{
	int nxt;
	int to;
	int w;
}e[300005];
int h[100007],e_cnt;
int anc[100007][23],dep[100007],maxn[100007][23];
int fa[100007];
int fi(int x){
	if(x!=fa[x])fa[x]=fi(fa[x]);
	return fa[x];
}
void hb(int x,int y){
	fa[x]=y;
	return;
}
bool cmp(pre_edge x,pre_edge y){
	return x.w<y.w;
}
void MST(){
	sort(pre_e+1,pre_e+m+1,cmp);
	for(int i=1;i<=n;++i)fa[i]=i;
	int cho_e=0;
	for(int i=1;i<=m;++i){
		int x=pre_e[i].to,y=pre_e[i].from;
		int fa_x=fi(x),fa_y=fi(y);
		if(fa_x!=fa_y){
			hb(fa_x,fa_y);
			++cho_e;
			add_edge(x,y,pre_e[i].w);
			add_edge(y,x,pre_e[i].w);
			if(cho_e==n-1)return;
		}
	}
	return;
}
void dfs(int now,int fro){
	dep[now]=dep[fro]+1;
	anc[now][0]=fro;
	for(int i=1;i<=16;++i){
		anc[now][i]=anc[anc[now][i-1]][i-1];
		maxn[now][i]=max(maxn[now][i-1],maxn[anc[now][i-1]][i-1]);
	}
	for(int i=h[now];i;i=e[i].nxt){
		int to=e[i].to;
		if(to==fro)continue;
		maxn[to][0]=e[i].w;
		dfs(to,now);
	}
	return;
}
int lca(int x,int y){
	int ans=0;
	if(dep[x]<dep[y])swap(x,y);
	for(int i=16;i>0;--i)
		if(dep[anc[x][i]]>dep[y]){
			ans=max(ans,maxn[x][i]);
			x=anc[x][i];
		}
	if(x==y)return x;
	for(int i=16;i>0;--i)
		if(anc[x][i]!=anc[y][i]){
			ans=max(ans,maxn[x][i]);
			ans=max(ans,maxn[y][i]);
			x=anc[x][i];
			y=anc[y][i];
		}
	ans=max(ans,maxn[x][0]);
	ans=max(ans,maxn[y][0]);
	return ans;
}
int main(){
	n=Read();m=Read();
	for(int i=1;i<=m;++i){
		int a=Read(),b=Read(),l=Read();
		pre_e[i].to=b;pre_e[i].from=a;pre_e[i].w=l;
	}
	MST();
	dfs(1,0);
	q=Read();
	for(int i=1;i<=q;++i){
		int a=Read(),b=Read();
		if(dep[a]==0||dep[b]==0)printf("impossible\n");
		else printf("%d\n",lca(a,b));
	}
    return 0;
}
void add_edge(int u,int v,int w){
	e[++e_cnt].to=v;
	e[e_cnt].w=w;
	e[e_cnt].nxt=h[u];
	h[u]=e_cnt;
	return;
}
int Read(){
	char ch=getchar();
	int res=0,flag=1;
	while(ch<'0'&&ch>'9'){
		if(ch=='-')flag=-1;
		ch=getchar();
	}
	while(ch>='0'&&ch<='9'){
		res=(res<<1)+(res<<3)+ch-'0';
		ch=getchar();
	}
	return flag*res;
}