qtsume

#include <bits/stdc++.h>
using namespace std;
int a[100001];
unsigned long long int s1[100001],s2[100001];

int main()
{
    int n,q,x,y;
    ifstream f("qtsume.in");
    f>>n>>a[1];
    s1[1]=s2[1]=a[1];
    for(int i=2;i<=n;++i)
        f>>a[i],s1[i]=s1[i-1]+1ULL*a[i],s2[i]=s2[i-1]+1ULL*i*a[i];
    f>>q;
    ofstream g("qtsume.out");
    while(q--)
        f>>x>>y,g<<s2[y]-s2[x-1]-(x-1)*(s1[y]-s1[x-1])<<'\n';
    return 0;
}