#include <bits/stdc++.h>
using namespace std;
const int P = 1e9 + 7, INF = 0x3f3f3f3f;
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long qpow(long long a, long long n) {
  long long r = 1 % P;
  for (a %= P; n; a = a * a % P, n >>= 1)
    if (n & 1) r = r * a % P;
  return r;
}
long long inv(long long first) {
  return first <= 1 ? 1 : inv(P % first) * (P - P / first) % P;
}
inline int rd() {
  int first = 0;
  char p = getchar();
  while (p < '0' || p > '9') p = getchar();
  while (p >= '0' && p <= '9') first = first * 10 + p - '0', p = getchar();
  return first;
}
const int N = 1e6 + 50;
int n, m, w[N], dep[N];
vector<pair<int, int>> g[N];
vector<pair<int, long long>> route[N];
void dfs(int first, int d) {
  dep[first] = d;
  for (auto &e : g[first]) dfs(e.first, d + e.second);
}
int p(int f, int first) {
  if (first == f * 2) return first + 1;
  return first - 1;
}
long long qry(int a, int h, int c) {
  if (a > n || c > h) return 0;
  auto p = --upper_bound(route[a].begin(), route[a].end(),
                         pair<int, long long>(h - c, 1e18));
  long long cnt = p - route[a].begin() + 1;
  return cnt * (h - c) - p->second;
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 2; i <= n; ++i) {
    int u = i / 2, v = i;
    scanf("%d", w + i);
    g[u].push_back({v, w[i]});
  }
  dfs(1, 0);
  for (int i = 1; i <= n; ++i) {
    int j = i;
    route[i].push_back({0, 0ll});
    while (j != 1) {
      j /= 2;
      route[j].push_back({dep[i] - dep[j], 0ll});
    }
  }
  for (int i = 1; i <= n; ++i) {
    sort(route[i].begin(), route[i].end());
    int sz = route[i].size();
    for (int j = 1; j <= sz - 1; ++j)
      route[i][j].second = route[i][j].first + route[i][j - 1].second;
  }
  while (m--) {
    int a, h;
    scanf("%d%d", &a, &h);
    long long ans = qry(a, h, 0);
    int c = 0;
    while (1) {
      c += w[a];
      if (a == 1 || c > h) break;
      int t = p(a / 2, a);
      ans += qry(t, h, c + w[t]);
      ans += h - c;
      a /= 2;
    }
    printf("%lld\n", ans);
  }
}
