#include<iostream>
using namespace std;

int main(){
int n,m,a,b;
while(scanf("%d%d",&n,&m)){
int score[n];
for(int i=1;i<=n;i++){
scanf("%d",&score[i]);
}
for(int j=1;j<=m;j++){
scanf("%d%d",&a,&b);int s=0;
for(int k=a;k<=b;k++){
s=s+score[k];
}printf("%d\n",s);
}
}
}

你少了最最最重要的EOF了喔
我多打EOF就對了