BIT or Fenwick tree

// Bhupendra Yadav
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
//#include < ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef tree<pair < int, int >, null_type, less<pair < int, int >>, rb_tree_tag, tree_order_statistics_node_update>  bhupixb;
const int N = 1001231;
typedef long long int ll;
ll bit[N];
// Remember the array is 0 indexd
#define f(i,a,n)   for(int i = a; i < n ; i++)
ll ret_sum(int i,int n){
    ll sum(0);
    while(i > 0){  // i > 0
        sum += bit[i];
        i -= (i & (-i));
    }
    return sum;
}
void update(int i, int num, int n){
    while(i <= n){ // i <= n Remember
        bit[i] += num;
        i += (i&(-i));
    }
}
int main(){
    int n, k, i;long int num;
    cin >> n;
    //VL v(n+1), arr(n+1, 0};
    f(i,0,n)cin >> num, update(i+1, num, n);
    cin >> k;
    while(k--){
        char ch; int l, r, val;
        cin >> ch;
        if(ch == 'q'){
            cin >> l >> r;
            cout << ret_sum(r, n) - ret_sum(max(0,l-1), n) << '\n';
        }
        else{
            cin >> i >> val;
            update(i, val, n);
        }
    }


return 0;
}