using System;

using System.Collections.Generic;

​

class Solution

{

    public static List<long> rangeSum(List<int> A, List<List<int>> B)

    {

        Console.WriteLine("START.....");

        int n = A.Count;

        List<long> pf = new List<long>(new long[n]);

        Console.WriteLine("START....." + A[0]);

        Console.WriteLine("START....." + pf.Count);

        pf[0] = A[0];

        for (int i = 1; i < n; i++)

        {

            Console.WriteLine("i :" + i);

            pf[i] = pf[i - 1] + A[i];

        }

​

        List<long> rangeSumAns = new List<long>(new long[B.Count]);

        for (int j = 0; j < B.Count; j++)

        {

            Console.WriteLine("j :" + j);

            int start = B[j][0];

            int end = B[j][1];

            Console.WriteLine("start :" + start + " end: " + end);

            if (start == 0)

            {

                rangeSumAns[j] = pf[end];

            }

            else

            {

                rangeSumAns[j] = pf[end] - pf[start];

            }

        }

​

        return rangeSumAns;

    }

}

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        var arr = new List<int>

        {

            7,

            3,

            1,

            5,

            5,

            5,

            1,

            2,

            4,

            5

        };

        var query = new List<List<int>>

        {

            new List<int>

            {

                6,

                9

            },

            new List<int>

            {

                2,

                9

            },

            new List<int>

            {

                2,

                4

            },

            new List<int>

            {

                0,

                9

            }

        };

        var ans = Solution.rangeSum(arr, query);

        Console.WriteLine("Ans: " + ans);

    }

}