#include<bits/stdc++.h>
#define int long long
#define N 1005
using namespace std;
int n,q,a[N],u[N],v[N],w[N],dis[N][N],x,y,maxx,juhua[200005],xx,yy; 
bool flag1=1,flag2=1;
int vis[N][N];
signed main() {
	freopen("poitry.in","r",stdin);
	freopen("poitry.out","w",stdout);
	memset(vis,0x3f,sizeof(vis));
	scanf("%lld%lld",&n,&q);
	for(int i=1;i<=n;i++){
		scanf("%lld",&a[i]);
	}
	for(int i=1;i<n;i++){
		scanf("%lld%lld%lld",&u[i],&v[i],&w[i]);
		if(v[i]!=u[i]+1)flag2=0;
		if(u[i]!=1)flag1=0;
	}
	if(!flag1&&!flag2){
		for(int i=1;i<n;i++){
			vis[u[i]][v[i]]=vis[v[i]][u[i]]=w[i];
		}
		for(int k=1;k<=n;k++){
			for(int i=1;i<=n;i++){
				for(int j=1;j<=n;j++){
					vis[i][j]=min(vis[i][j],vis[i][k]+vis[k][j]);
					vis[j][i]=vis[i][j];
				}
			}
		}
		while(q--){
			scanf("%lld%lld",&x,&y);
			maxx=1e12;
			xx=min(x,y);
			yy=max(x,y);
			for(int i=xx;i<=yy;i++){
				maxx=min(maxx,max(a[i],vis[i][x]));
			}
			cout<<maxx<<'\n';
		}
		return 0;
	}
	return 0;
}