#include <fstream.h>
#include <values.h>
long k,n,max=-MAXLONG,a[100000],xx,yy,in;
ifstream fin("sequencequery.in");
void citire(){
fin>>n>>k;
for (long i=0;i<n;i++)
  fin>>a[i];
}


long parc(long k){
long max=-MAXLONG,S=0;
for (long i=xx;i<xx+k;i++)
     S+=a[i];
if (S>max)
   max=S;
for (long j=xx+k;j<=yy;j++){
    S-=a[j-k];
    S+=a[j];
    if (S>max)
       max=S;
   }
return max;
}

int main(){
long maxim=0,aux;
citire();
ofstream fout("sequencequery.out");
for (long i=0;i<k;i++)             {
   fin>>xx>>yy;
   maxim=-124515;
   xx--;
   yy--;
   for (long k=1;k<=yy-xx+1;k++){
	   aux=parc(k);
   if (aux>maxim)
      maxim=aux; 
   }
   fout<<maxim<<"\n";                   }
fin.close();
fout.close();
return 0;
}