#include <bits/stdc++.h>
#define ll long long
#define ldb long double
#define endl '\n'
#define For(i,l,r) for(int i=l;i<=r;i++)
#define ForD(i,r,l) for(int i=r;i>=l;i--)
#define REP(i,l,r) For(i,l,r-1)
#define PER(i,r,l) ForD(i,r-1,l)
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
#define All(x,n) x+1,x+1+n
#define Alll(x,n) x,x+n
#define sz(x) (signed)x.size()
#define unq(x) x.resize(unique(all(x))-x.begin())
#define mpa make_pair
#ifdef NCGM
#include"debug.h"
#else
#define debug(...) "fr";
#endif
using namespace std;
const int N=3e5+3;
int n,q;
ll d,c[N];
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> d;
For(i,1,n) cin >> c[i];
cin >> q;
while(q--) {
int l,r;
cin >> l >> r;
ll ans=0,cur=c[r];
ForD(k,r-1,l) {
if (c[k]<=cur) {
cur=c[k];
continue;
}
ll sus=(c[k]-cur)/d;
while (c[k]-sus*d>cur) sus++;
ans+=sus;
cur=c[k]-sus*d;
}
if (cur>=0) cout << ans << endl;
else cout << -1 << endl;
}
return 0;
}
