#include<bits/stdc++.h> 
using namespace std;
int a[1000021],b[1000021];
int main(){
	int x,y,n,e,l,r;
	scanf("%d %d",&n,&x);
	b[0]=1;
for (int i=1;i<=n;i++)
{scanf("%d ",&a[i]);
b[i]=b[i-1]*a[i];
a[i]+=a[i-1];}
for (int i=1;i<=x;i++)
{scanf("%d %d %d",&l,&r,&y);
if (abs(a[r]-a[l-1]-y)<=a[r]-a[l-1])
printf("%d\n",abs(a[r]-a[l-1]-y)-b[r]);
else printf("-1\n");}
	return 0;
}