#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define all(s) s.begin(),s.end()
#define rall(s) s.rbegin(),s.rend()
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
ll n,d;
cin>>n>>d;
vector<ll>v;
ll c[n+5],pre[n+5];
pre[0]=0;
for(ll i=1;i<=n;i++){
cin>>c[i];
pre[i]=pre[i-1]+c[i];//0,1
if(c[i]==0){
v.pb(i);
}
}
ll q;
cin>>q;
ll a[n+5];
while(q--){
ll l,r;
cin>>l>>r;
if(pre[r]-pre[l-1]==r-l+1){
cout<<0<<"\n";
continue;
}
ll p=v[upper_bound(all(v),r)-v.begin()-1];
ll ans=0;
if(pre[p]-pre[l-1]>0){
if(d!=1){
cout<<-1<<"\n";
continue;
}
ans=pre[p]-pre[l-1];
}
cout<<ans<<"\n";
}
}
