#include <bits/stdc++.h>

#define f first
#define s second
#define pb push_back
#define mp make_pair

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;

const int N = 300500, inf = 1e9, mod = 998244353;
const ll INF = 1e18;

int sum(int a, int b) {
    a += b;
    if (a >= mod)
        a -= mod;
    return a;
}

int sub(int a, int b) {
    a -= b;
    if (a < 0)
        a += mod;
    return a;
}

int mult(int a, int b) {
    return 1ll * a * b % mod;
}

int bp(int a, int b) {
    int res = 1;
    while (b) {
        if (b & 1)
            res = mult(res, a);
        a = mult(a, a);
        b >>= 1;
    }
    return res;
}

int inv(int x) {
    return bp(x, mod - 2);
}

int n, q;
ll a[N], s;
ll b[N];

/*
 1 0 1
 2 1 0
 3 0 0
 4 2 0
 5 2 1
 6 3 0
 */
void solve() {
    cin >> n >> q;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        s += a[i];
    }
    while (q--) {
        int p, x;
        {
            cin >> p >> x;
            s += x;
            a[p] += x;
        }
        ll ans = 0;
        for (int i = 1; i <= n; i++)
            b[i] = a[i];
        for (int i = n, j = n; i >= 1; i--) {
            while (b[i] >= 2) {
                j = min(j, i + i - 1);
                while (j > i && b[j] == 0)
                    j--;
                if(j == i)
                    break;
                int x = min(b[i] / 2, b[j]);
                b[i] -= 2 * x;
                b[j] -= x;
                ans += x;
            }
            ans += b[j] / 3;
            b[j] %= 3;
        }
        cout << ans << "\n";
    }
}

int main() {
#ifdef DEBUG
    freopen("input.txt", "r", stdin);
#endif
    ios_base::sync_with_stdio(false);
    int t = 1;
//    cin >> t;
    for (int i = 1; i <= t; i++) {
//        cout << "Case #" << i << endl;
        solve();
    }
}