#include <bits/stdc++.h>
using i64 = long long;
#ifdef DEBUG
#include "/home/ahmetalp/Desktop/Workplace/debug.h"
#else
#define debug(...) void(23)
#endif
constexpr int max_N = int(3E5) + 5;
constexpr i64 inf = i64(1E18);
int N;
i64 D;
i64 A[max_N];
int Q;
int L[max_N];
int R[max_N];
i64 ans[max_N];
std::vector<int> ask[max_N];
#define def int mid = (l + r) >> 1, lv = v + 1, rv = v + ((mid - l + 1) << 1)
struct segtree {
struct node {
i64 sum = 0;
i64 lz = 0;
int len = 0;
void modify(i64 x) {
sum += x * len;
lz += x;
}
};
node unite(const node& lhs, const node& rhs) {
node res;
res.sum = lhs.sum + rhs.sum;
res.len = lhs.len + rhs.len;
return res;
}
int n;
std::vector<node> tree;
segtree(int n_) : n(n_), tree(n << 1) {
auto dfs = [&](auto&& self, int v, int l, int r) -> void {
if (l == r) {
tree[v] = {0, 0, 1};
return;
}
def;
self(self, lv, l, mid);
self(self, rv, mid + 1, r);
tree[v] = unite(tree[lv], tree[rv]);
};
dfs(dfs, 0, 0, n - 1);
}
void push(int v, int l, int r) {
def;
if (tree[v].lz) {
tree[lv].modify(tree[v].lz);
tree[rv].modify(tree[v].lz);
tree[v].lz = 0;
}
}
void modify(int v, int l, int r, int ql, int qr, i64 x) {
if (ql == l && r == qr) {
tree[v].modify(x);
return;
}
def;
push(v, l, r);
if (qr <= mid) {
modify(lv, l, mid, ql, qr, x);
} else if (mid + 1 <= ql) {
modify(rv, mid + 1, r, ql, qr, x);
} else {
modify(lv, l, mid, ql, mid, x);
modify(rv, mid + 1, r, mid + 1, qr, x);
}
tree[v] = unite(tree[lv], tree[rv]);
}
void modify(int l, int r, i64 x) {
modify(0, 0, n - 1, l, r, x);
}
node get(int v, int l, int r, int ql, int qr) {
if (ql == l && r == qr) {
return tree[v];
}
def;
push(v, l, r);
if (qr <= mid) {
return get(lv, l, mid, ql, qr);
} else if (mid + 1 <= ql) {
return get(rv, mid + 1, r, ql, qr);
} else {
return unite(get(lv, l, mid, ql, mid),
get(rv, mid + 1, r, mid + 1, qr));
}
}
node get(int l, int r) {
return get(0, 0, n - 1, l, r);
}
};
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
std::cin >> N >> D;
for (int i = 0; i < N; ++i) {
std::cin >> A[i];
}
std::cin >> Q;
for (int i = 0; i < Q; ++i) {
std::cin >> L[i] >> R[i];
--L[i], --R[i];
ask[R[i]].emplace_back(i);
}
segtree sega(N);
segtree segans(N);
for (int i = 0; i < N; ++i) {
sega.modify(i, i, A[i]);
}
std::vector<std::pair<int, i64>> stk;
stk.emplace_back(0, inf);
std::vector<i64> sum(N);
for (int i = 1; i < N; ++i) {
if (A[i - 1] <= A[i]) {
stk.emplace_back(i, (A[i] - A[i - 1]) / D);
} else {
i64 need = (A[i - 1] - A[i] + D - 1) / D;
while (need) {
auto&[j, v] = stk.back();
i64 use = std::min(v, need);
sega.modify(j, i - 1, -use * D);
segans.modify(j, i - 1, use);
// for (int k = j; k < i; ++k) {
// A[k] -= use * D;
// sum[k] += use;
// }
v -= use;
need -= use;
if (v == 0) {
stk.pop_back();
}
}
}
for (auto j : ask[i]) {
if (sega.get(L[j], L[j]).sum < 0) {
ans[j] = -1;
} else {
ans[j] = segans.get(L[j], i).sum;
}
// if (A[L[j]] < 0) {
// ans[j] = -1;
// } else {
// i64 res = 0;
// for (int k = j; k <= i; ++k) {
// res += sum[k];
// }
// ans[j] = res;
// }
}
}
for (int i = 0; i < Q; ++i) {
std::cout << ans[i] << '\n';
}
return 0;
}
