#include<stdio.h>
#define M -200000
long long n,m,c[100001],a[100001],l,y,x,k,max=M;
int main()
{
	long long i,j;
	freopen("sequencequery.in","r",stdin);
	freopen("sequencequery.out","w",stdout);
	scanf("%ld %ld",&n,&m);
	for(i=1;i<=n;++i)
		scanf("%ld",&a[i]);
	for(;m;--m){
		scanf("%ld %ld",&x,&y);
		l=y-x+1;
		for(i=l;i>=1;--i){
			++k;
			for(j=x;j<=j+i-1;++j)
				c[k]+=a[j];
		}
		for(i=1;i<=k;++i){
			if(max<c[i])
				max=c[i];
			c[i]=0;
		}
		printf("%ld\n",max);
		max=M;
		k=0;
	}
	return 0;
}