#include <bits/stdc++.h>
void solve() {
int n, d;
std::cin >> n >> d;
std::vector<int64_t> a(n + 1);
for(int i = 1; i <= n; i++) {
std::cin >> a[i];
}
int q;
std::cin >> q;
while(q--) {
int l, r;
std::cin >> l >> r;
if(is_sorted(a.begin() + l, a.begin() + r + 1)) {
std::cout << 0 << "\n";
continue;
}
int can = 1;
int ans = 0;
std::vector<int64_t> f = a;
for(int i = l; i < r; i++) {
while(f[i] > f[i + 1]) {
f[i] -= d;
ans += 1;
}
if(f[i] < 0) {
can = 0;
}
}
std::cout << (can == 0 ? - 1 : ans) << "\n";
}
}
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
int t = 1;
//std::cin >> t;
while (t--) {
solve();
}
return 0;
}
