#include <bits/stdc++.h>
using std::cin;
using std::cout;
using std::endl;
using std::vector;
using std::string;
using ll = long long;
using vi = vector<ll>;
using vii = vector<vi>;
using pii = std::pair<ll,ll>;

#define ln "\n"
#define rep(i,j,k) for(ll i=ll(j); i<ll(k); i++)
#define REP(i,j,k) for(ll i=ll(j); i<=ll(k); i++)
#define per(i,j,k) for(ll i=ll(j); i>=ll(k); i--)
#define all(a) a.begin(), a.end()
#define pb emplace_back
#define mp std::make_pair

constexpr ll inf = (1ll<<60);

int main(){
    ll N,Q; cin >> N >> Q;
    assert(N*Q <= 1e7);
    vi C(N);
    rep(i,0,N) cin >> C[i];
    while(Q--){
        ll l,d; cin >> l >> d;
        C[l-1] += d;
        vi memC = C;
        vi A(N);
        ll ans = 0;
        rep(i,0,N) ans += C[i];
        ll right = N-1;
        ll min = 0;
        ll sum = 0;
        per(i,2*N-1,0){
            if(i%2 == 0) sum += C[i/2]/2;
            if(i < N) sum -= C[i]%2;
            min = std::min(min, sum);
        }
        cout << (ans+min)/3 << ln;
        C = memC;
    }
}