#include<bits/stdc++.h>
#define ll long long
#define maxn 300005
using namespace std;
int n;
ll d;
ll a[maxn];
ll b[maxn];
ll dif[maxn];
ll sdif[maxn];
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n>>d;
for(int i=1;i<=n;i++)
{
cin>>a[i];
}
for(int i=1;i<n;i++)
{
dif[i]=((a[i+1]-a[i])%d+d)%d;
sdif[i]=sdif[i-1]+dif[i];
}
int q;
cin>>q;
while(q--)
{
int l,r;
cin>>l>>r;
int flag=0;
for(int i=l;i<=r;i++)
{
b[i]=(a[i]-sdif[i-1]);
//Voi mot thang r co dinh thi tat cac so chi cong
//len mot luong co dinh
//(a[i]-sdif[i-1])+(sdif[l-1]-a[l]%d)>=0
if((a[i]-sdif[i-1])+(sdif[l-1]-a[l]%d)<0)
{
flag=1;
break;
}
//cout<<b[i]<<' ';
}
//cout<<'\n';
if(flag)
{
cout<<-1<<'\n';
continue;
}
//cout<<'\n';
int pre=r;
ll sum=b[r];
ll ds=0;
for(int i=r-1;i>=l;i--)
{
if(b[i]>=b[pre])
{
sum+=b[i];
}
else
{
//cout<<pre<<' '<<i<<'\n';
ds+=(sum- (pre-i)*b[pre] );
pre=i;
sum=b[i];
}
}
//cout<<sum<<' '<<pre<<'\n';
ds+=sum-(pre-l+1)*b[pre];
cout<<ds/d<<'\n';
}
}
/*
s[i]=s[i-3]+(a[i-2]-s[i-3])%mod+(a[i-1]-a[i-2])%mod+(a[i]-a[i-1])%mod
s[i]=(a[l])%mod+(a[l+1]-a[l])%mod+...+(a[i]-a[i-1])%mod
(a[i]-sdif[i-1])+(sdif[l-1]-a[l]%d)
*/
