#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }


int N, Q;
vector<Int> C;

Int brute() {
  auto check = [&](Int tar) -> bool {
    vector<Int> one(N + 1), two(N + 1);
    {
      Int lot = tar;
      for (int i = N; i >= 1; --i) {
        const Int t = min(C[i] / 2, lot);
        lot -= t;
        one[i] = C[i] - 2 * t;
        two[i] = t;
      }
    }
    int i = 1;
    for (int j = 1; j <= N; ++j) {
      for (; two[j] > 0; ) {
        const int limI = min(2 * j - 1, N);
        if (i > limI) {
          return false;
        } else if (one[i] == 0) {
          ++i;
        } else {
          const Int t = min(one[i], two[j]);
          one[i] -= t;
          two[j] -= t;
        }
      }
    }
    return true;
  };
  Int lo = 0, hi = 0;
  for (int i = 1; i <= N; ++i) {
    hi += C[i] / 2;
  }
  hi += 1;
  for (; lo + 1 < hi; ) {
    const Int mid = (lo + hi) / 2;
    (check(mid) ? lo : hi) = mid;
  }
// cerr<<"brute "<<C<<" = "<<lo<<endl;
  return lo;
}

Int slow() {
  Int sumTwo = 0;
  vector<Int> fs(N + 1, 0);
  for (int i = 1; i <= N; ++i) {
    const Int one = C[i] % 2;
    const Int two = C[i] / 2;
    sumTwo += two;
    fs[i] += one;
    fs[min(2 * i - 1, N)] -= two;
  }
  Int mn = 0;
  Int now = 0;
  for (int i = 1; i <= N; ++i) {
    now += fs[i];
    chmin(mn, now);
  }
  Int ans = sumTwo;
  // 2 -> 1,1
  ans -= (-mn + 2) / 3;
  return ans;
}


struct Data {
  Int sum, mn;
  Data(Int val = 0) : sum(val), mn(min(val, 0LL)) {}
  void pull(const Data &l, const Data &r) {
    sum = l.sum + r.sum;
    mn = min(l.mn, l.sum + r.mn);
  }
};

int main() {
  for (; ~scanf("%d%d", &N, &Q); ) {
    C.assign(N + 1, 0);
    for (int i = 1; i <= N; ++i) {
      scanf("%lld", &C[i]);
    }
    
    Int sumTwo = 0;
    vector<Int> fs(N + 1, 0);
    auto add = [&](int i, int sig) -> void {
      const Int one = C[i] % 2;
      const Int two = C[i] / 2;
      sumTwo += sig * two;
      fs[i] += sig * one;
      fs[min(2 * i - 1, N)] -= sig * two;
    };
    
    for (int i = 1; i <= N; ++i) {
      add(i, +1);
    }
    
    int segN;
    for (segN = 1; segN < N + 1; segN <<= 1) {}
    vector<Data> seg(segN << 1);
    for (int i = 0; i < N; ++i) {
      seg[segN + i] = Data(fs[i]);
    }
    for (int u = segN; --u; ) {
      seg[u].pull(seg[u << 1], seg[u << 1 | 1]);
    }
    auto update = [&](int i) -> void {
      int u = segN + i;
      seg[u] = Data(fs[i]);
      for (; u >>= 1; ) {
        seg[u].pull(seg[u << 1], seg[u << 1 | 1]);
      }
    };
    
    for (int q = 0; q < Q; ++q) {
      int L;
      Int D;
      scanf("%d%lld", &L, &D);
      
      add(L, -1);
      C[L] += D;
      add(L, +1);
      
      update(L);
      update(min(2 * L - 1, N));
      
      Int ans = sumTwo;
      ans -= (-seg[1].mn + 2) / 3;
      printf("%lld\n", ans);
#ifdef LOCAL
const Int brt=brute();
if(brt!=ans){
 cerr<<C<<": "<<brt<<" "<<ans<<endl;
 assert(brt==ans);
}
#endif
    }
  }
  return 0;
}