GSS1 - Can you answer these queries I

GSS1 - Can you answer these queries I

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You are given a sequence A[1], A[2], ..., A[N] . ( |A[i]| ≤ 15007 , 1 ≤ N ≤ 50000 ). A query is defined as follows: 
Query(x,y) = Max { a[i]+a[i+1]+...+a[j] ; x ≤ i ≤ j ≤ y }. 
Given M queries, your program must output the results of these queries.

Input

• The first line of the input file contains the integer N.
• In the second line, N numbers follow.
• The third line contains the integer M.
• M lines follow, where line i contains 2 numbers xi and yi.

Output

Your program should output the results of the M queries, one query per line.

Example

Input:
3 
-1 2 3
1
1 2
Output:
2

####################################CODE########################################################

#include<iostream>
using namespace std;
typedef long long int lli;
lli  qs,qe;
lli arr[5000100];
#include<bits/stdc++.h>
long long int read_int(){
 char r;
 bool start=false,neg=false;
 long long int ret=0;
 while(true){
  r=getchar();
  if((r-'0'<0 || r-'0'>9) && r!='-' && !start){
   continue;
  }
  if((r-'0'<0 || r-'0'>9) && r!='-' && start){
   break;
  }
  if(start)ret*=10;
  start=true;
  if(r=='-')neg=true;
  else ret+=r-'0';
 }
 if(!neg)
  return ret;
 else
  return -ret;
}
struct node 
 {
  lli pf,sf,max_sum,tot_sum;
  
 } seg[1000100];
 
 void build(int index ,int start,int end)
  {
   if(start==end)
    {
     seg[index].pf=arr[start];
     seg[index].sf=arr[start];
     seg[index].max_sum=arr[start];
     seg[index].tot_sum=arr[start];
    }
    else if(start>end) return ;
    else
    {
     build(2*index,start,(start+end)/2);
     build(2*index+1,(start+end)/2+1,end);
     seg[index].pf=max(seg[2*index].pf,seg[2*index].tot_sum+seg[2*index+1].pf);
     seg[index].sf=max(seg[2*index+1].sf,seg[2*index+1].tot_sum+seg[2*index].sf);
     seg[index].tot_sum=seg[2*index].tot_sum+seg[2*index+1].tot_sum;
     seg[index].max_sum=max(seg[2*index].max_sum,max(seg[2*index+1].max_sum,seg[2*index].sf+seg[2*index+1].pf));
    }
  }
   node  query(int index ,int start,int end)
   {
    
      if(start>end || start>qe || end<qs)
   {
     node inf;
 inf.pf=-999999999;
 inf.sf=-999999999;
 inf.max_sum=-999999999;
 inf.tot_sum=-999999999;
    return inf;
   } 
      else if(qs<=start && qe>=end) 
       {
        
  return seg[index];    
       }
       
        
         node node1= query(2*index,start,(start+end)/2);
         node node2= query(2*index+1,(start+end)/2+1,end);
         node rnode;
        
     rnode.pf=max(node1.pf,node1.tot_sum+node2.pf);
     rnode.sf=max(node2.sf,node2.tot_sum+node1.sf);
     rnode.tot_sum=node1.tot_sum+node2.tot_sum;
     rnode.max_sum=max(node1.max_sum,max(node2.max_sum,node1.sf+node2.pf));
     return rnode;
        
   }
int main()
 {
   int n;
    cin>>n;
     for(int i=0;i<n;i++)
      arr[i]=read_int();
      build(1,0,n-1);
 /*     for(int i=1;i<2*n+10;i++)
       cout<<i<<" "<<seg[i].tot_sum<<" "<<seg[i].pf<<" "<<seg[i].sf<<" "<<seg[i].max_sum<<endl;*/
       lli q;
      //   cin>>q;
      q=read_int();
         while(q--)
          {
           //cin>>qs>>qe;
           qs=read_int();
           qe=read_int();
           qs-=1;
           qe-=1;
            node ans=query(1,0,n-1);
            //cout<<ans.max_sum<<endl;
            printf("%lld\n",ans.max_sum);
          }
      return 0;
      
 }