#ifndef SorahISA
#define SorahISA
#include SorahISA __FILE__ SorahISA

void solve() {
    int N, Q; cin >> N >> Q;
    
    vector<int> C(N+1);
    for (int i = 1; i <= N; ++i) cin >> C[i];
    
    for (int q = 1; q <= Q; ++q) {
        int l, d; cin >> l >> d, C[l] += d;
        
        int ans = 0;
        for (int i = 1, j = 0, sum = 0; i <= N; ++i) {
            while (j <= min(N, 2*i-1)) sum += (C[j++] == 1);
            int tmp = min(C[i] / 2, (C[i] + sum) / 3);
            ans += tmp, sum = C[i] + sum - 3 * tmp;
        }
        cout << ans << "\n";
    }
}

int32_t main() {
    fastIO();
    
    int t = 1; // cin >> t;
    for (int _ = 1; _ <= t; ++_) {
        solve();
    }
    
    return 0;
}

#else

#ifdef local
#define _GLIBCXX_DEBUG 1
#endif
#pragma GCC optimize("Ofast", "unroll-loops")
#include <bits/stdc++.h>
using namespace std;

using i64 = long long;
#define int i64
using f80 = long double;
#define double f80
using pii = pair<int, int>;
template <typename T> using Prior = std::priority_queue<T>;
template <typename T> using prior = std::priority_queue<T, vector<T>, greater<T>>;

#define eb emplace_back
#define ef emplace_front
#define ee emplace
#define pb pop_back
#define pf pop_front
#define ALL(x) begin(x), end(x)
#define RALL(x) rbegin(x), rend(x)
#define SZ(x) ((int)(x).size())

#ifdef local
#define fastIO() void()
#define debug(...) \
    fprintf(stderr, "\u001b[33m"), \
    fprintf(stderr, "At [%s], line %d: (%s) = ", __FUNCTION__, __LINE__, #__VA_ARGS__), \
    _do(__VA_ARGS__), \
    fprintf(stderr, "\u001b[0m")
template <typename T> void _do(T &&_t) { cerr << _t << "\n"; }
template <typename T, typename ...U> void _do(T &&_t, U &&..._u) { cerr << _t << ", ", _do(_u...); }
#else
#define fastIO() ios_base::sync_with_stdio(0), cin.tie(0)
#define debug(...) void()
#endif

template <typename T, typename U> bool chmin(T &lhs, U rhs) { return lhs > rhs ? lhs = rhs, 1 : 0; }
template <typename T, typename U> bool chmax(T &lhs, U rhs) { return lhs < rhs ? lhs = rhs, 1 : 0; }

#endif