SO EASY

#include<cstdio>
using namespace std;
typedef int INT;
const INT MAXN=100000;
INT main(){
    INT a[MAXN],n,m;a[0]=0;
    scanf("%d%d",&n,&m);
    for(INT i=1;i<=n;i++){
        scanf("%d",&a[i]);
        a[i]+=a[i-1];
    }
    while(m--){
        INT l,r;
        scanf("%d%d",&l,&r);
        printf("%d\n",a[r]-a[l-1]);
    }
}