[BOJ] 11659. 구간 합 구하기 4

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int N,M;
		int arr[];
		int sum[];
		N=sc.nextInt();
		M=sc.nextInt();
		arr=new int[N+1];
		sum=new int[N+1];
		sum[0]=0;
		for (int x = 1; x <= N; x++) {
			arr[x]=sc.nextInt();
			if(x==1) {
				sum[1]=arr[1];
			}else {
				sum[x]=sum[x-1]+arr[x];
			}
		}
		
		for (int x = 1; x <= M; x++) {
			int i=sc.nextInt();
			int j=sc.nextInt();
			System.out.println(sum[j]-sum[i-1]);
		}
	}
}