//#pragma target("arch=icelake-server")
#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <stack>
#include <queue>
#include <cmath>
#include <random>
#include <chrono>
#include <iomanip>
#include <bitset>
using namespace std;
#define int long long
typedef long long ll;
typedef long double ld;
int log_ = 11;
int inf = 4000000007000000007;
long long mod = 1000000007;
int p = 499;
int NADIYA = 39;
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int n , d;
cin >> n >> d;
vector <int> a(n);
for (int i = 0; i < n; i++)
cin >> a[i];
int q;
cin >> q;
for (int i = 0; i < q; i++)
{
int l, r;
cin >> l >> r;
l--;
r--;
int mx = a[r];
int ans = 0;
for (int j = r - 1; j >= l; j--)
{
if (mx > a[j])
{
mx = a[j];
}
else
{
int s = (a[j] - mx);
int col = s / d + ((s % d) > 0);
ans += col;
mx = a[j] - col * d;
}
}
if (mx < 0)
cout << -1 << "\n";
else
cout << ans << "\n";
}
}
/*5
1 2 1
2 3 1
2 4 1
1 5 4
*/
