#include <bits/stdc++.h>
using namespace std;
#define FI first
#define SE second
#define mkp make_pair

namespace FastIO {
	#define iL (1 << 20)
	char ibuf[iL],*iS = ibuf + iL,*iT = ibuf + iL;
	#define gc() (iS == iT ? (iT = (iS = ibuf) + fread(ibuf,1,iL,stdin),iS == iT ? EOF : *iS++) : *iS++)
	template<typename T>
	inline void read(T &a)
	{
		char ch;int sign = 0;
		for(ch = gc();!isdigit(ch);ch = gc())
			if(ch == '-') sign = 1;
		a = ch & 15;
		for(ch = gc();isdigit(ch);ch = gc())
			a = (a << 3) + (a << 1) + (ch & 15);
		if(sign) a = -a;
	}
	char Out[iL],*iter = Out;
	#define flush() fwrite(Out,1,iter - Out,stdout),iter = Out
	template<typename T>
	inline void write(T x,char end = '\n')
	{
		int c[40],l = 0;if(x < 0) *iter++ = '-',x = -x;
		do c[++l] = x % 10,x /= 10; while(x);
		while(l) *iter++ = c[l--] + '0';
		*iter++ = end;flush();
	}
	#undef iL 
	#undef gc
	#undef flush
}
using namespace FastIO;

const int N = 2e6 + 5;
int n,Q;
vector<pair<int,int> > G[N];
int p[N];
set<int> vals;
int fir[N],nxt[N << 1],to[N << 1],w[N << 1],ect = 1;
inline void addedge(int u1,int v1,int w1) {
	nxt[++ect] = fir[u1];fir[u1] = ect;to[ect] = v1;w[ect] = w1;
}
int sze[N],pminn,pid;
bool sgn[N << 1];
void findroot(int x,int S,int fa) {
	sze[x] = 1;
	for(int i = fir[x],y;y = to[i],i;i = nxt[i]) 
		if(y != fa && !sgn[i]) {
			findroot(y,S,x);
			sze[x] += sze[y];
			if(min(sze[y],S - sze[y]) > pminn)
				pminn = min(sze[y],S - sze[y]),pid = i;
		}
}
long long dep[N];
vector<int> V1,V2;
void dfs(int x,int fa,vector<int> &V) {
	V.push_back(x);
	for(int i = fir[x],y;y = to[i],i;i = nxt[i])
		if(!sgn[i] && y != fa) dep[y] = dep[x] + w[i],dfs(y,x,V);
}
vector<pair<long long,int> > Qs[N];
int Ans[N];
void Divide(int x,int S) {
	if(S <= 1) return;
	pminn = 0;findroot(x,S,0);
	int pu = to[pid],pv = to[pid ^ 1],pw = w[pid];
	int szeu = sze[pu],szev = S - sze[pu];
	V1.clear();V2.clear();
	sgn[pid] = sgn[pid ^ 1] = true;
	dep[pu] = dep[pv] = 0;
	dfs(pu,0,V1);dfs(pv,0,V2);
	// printf("pu,pv,pw:%d,%d,%d\n",pu,pv,pw);
	sort(V1.begin(),V1.end(),[&](const int &x,const int &y) { return dep[x] > dep[y];});
	sort(V2.begin(),V2.end(),[&](const int &x,const int &y) { return dep[x] > dep[y];});
	// printf("V1: ");for(auto i : V1) printf("(%d,%lld) ",i,dep[i]);printf("\n");
	// printf("V2: ");for(auto i : V2) printf("(%d,%lld) ",i,dep[i]);printf("\n");
	vector<pair<long long,int> > nQ;
	for(auto i : V2) for(auto [k,id] : Qs[i]) if(k >= dep[i] + pw) nQ.emplace_back(k - dep[i] - pw,id);
	sort(nQ.begin(),nQ.end(),[&](const pair<long long,int> &x,const pair<long long,int> &y) { return x.FI > y.FI;});
	int pos = 0,mn = 1e9;
	for(auto [v,id] : nQ) {
		while(pos < V1.size() && dep[V1[pos]] > v) mn = min(mn,p[V1[pos]]),++pos;
		Ans[id] = min(Ans[id],mn);
	}
	nQ.clear();
	for(auto i : V1) for(auto [k,id] : Qs[i]) if(k >= dep[i] + pw) nQ.emplace_back(k - dep[i] - pw,id);
	sort(nQ.begin(),nQ.end(),[&](const pair<long long,int> &x,const pair<long long,int> &y) { return x.FI > y.FI;});
	pos = 0,mn = 1e9;
	for(auto [v,id] : nQ) {
		while(pos < V2.size() && dep[V2[pos]] > v) mn = min(mn,p[V2[pos]]),++pos;
		// printf("pos:%d,%d,%d\n",pos,id,mn);
		Ans[id] = min(Ans[id],mn);
	}
	Divide(pu,szeu);Divide(pv,szev);
}
int tot;
void dfs0(int x,int fa) {
	int lst = x;
	for(auto [y,w] : G[x]) if(y != fa) {
		int now = ++tot;p[now] = 1e9;
	 	addedge(lst,now,0),addedge(now,lst,0);
		addedge(now,y,w);addedge(y,now,w);
		lst = now;
		dfs0(y,x);
	}
}
int main() {
	read(n);read(Q);
	for(int i = 1;i <= n;i++) read(p[i]),vals.insert(p[i]);
	int allmex = 0;
	while(vals.count(allmex)) ++allmex;
	tot = n;
	for(int i = 1,u,v,w;i < n;i++)
		read(u),read(v),read(w),G[u].emplace_back(v,w),G[v].emplace_back(u,w);
	for(int i = 1;i <= Q;i++) {
		int x;long long k;
		read(x);read(k);
		Qs[x].emplace_back(k,i);
		Ans[i] = allmex;
	}
	dfs0(1,0);Divide(1,tot);
	for(int i = 1;i <= Q;i++) write(Ans[i]);
	return 0;
}