#include<bits/stdc++.h>
using namespace std;
const int N=1000005;
const int logn=20;
int n,m,f[N][logn],log1[N];
struct qq{
	string s;
	string s1;
}a[N];
int bj(int x,int y){
	/*if(a[x].s>a[y].s)return x;
	else return y;*/
	int i=0;
	while(x/*i<=a[x].s.length()&&i<=a[y].s.length()*/){
		if(i>a[x].s.length())return y;
		if(i>a[y].s.length())return x;
		int xx=a[x].s[i],yy=a[y].s[i];
		//cout<<endl<<a[x].s.length()<<"  "<<a[y].s.length()<<" "<<xx<<"  "<<yy<<endl;
		if(xx<yy)return y;
		if(xx>yy)return x;
		i++;
		
	}
}
void print(int x){
	cout<<a[x].s1<<endl;
}
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		//scanf("%s",a[i].s_str());
		cin>>a[i].s;
		a[i].s1=a[i].s;
		int l=sizeof(a[i].s);
		for(int j=0;j<l;j++){
			if(a[i].s[j]>='a'&&a[i].s[j]<='z')a[i].s[j]-=32;
		}
		/*for(int j=0;j<=a[i].s1.length();j++){
			if(a[i].s1[j]>'Z'){
				a[i].s[j]=a[i].s1[j]-32;
			}
			else a[i].s[j]=a[i].s1[j];
			//cout<<a[i].s[j];
		}*/
		//cout<<a[i].s1<<endl;
		//cout<<a[i].s<<endl;
	}
	log1[0]=-1;
	for(int i=1;i<=n;i++){
		log1[i]=log1[i>>1]+1;
		f[i][0]=i;
	}
	for(int j=1;j<=logn;j++){
		for(int i=1;i+(1<<j)-1<=n;i++){
			//cout<<f[i][j-1]<<"    "<<f[i+(1<<j-1)][j-1]<<"   ";
			f[i][j]=bj(f[i][j-1],f[i+(1<<j-1)][j-1]);
			//cout<<i<<" "<<j<<" "<<f[i][j]<<endl;
		}
	}
	while(m--){
		int x,y;
		scanf("%d%d",&x,&y);
		int s=log1[y-x+1];
		int ans=bj(f[x][s],f[y-(1<<s)+1][s]);
		print(ans);
	}
	return 0;
}

十个全部re 但看不出来