#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
const int MAXN = 2e5 + 5;

struct Data
{
	ll sum, ans, rem;
	void init(int x)
	{
		sum = x;
		ans = x / 3;
		rem = x / 2 - ans;
	}
};
Data operator + (Data A,Data B)
{
	Data res;
	res.sum = A.sum + B.sum;
	res.ans = 0;
	res.rem = 0;
	
	ll use = min(B.rem, A.sum);
	res.ans += B.ans;
	res.ans += use;
	res.rem += B.rem - use;
	
	ll lim = (A.sum - use) / 3;
	lim = min(lim, A.ans);
	res.ans += lim;
	res.rem += A.ans + A.rem - lim;
	
	return res;
}

struct Segment_Tree
{
	Data tree[MAXN<<2];
	#define ls(u) ((u)<<1)
	#define rs(u) ((u)<<1|1)
	#define lson(u) ls(u),l,mid
	#define rson(u) rs(u),mid+1,r
	inline void push_up(int u)
	{
		tree[u] = tree[ls(u)] + tree[rs(u)];
	}
	void build(int u,int l,int r,int *a)
	{
		if(l == r){ tree[u].init(a[l]); return;}
		int mid = (l+r)>>1;
		build(lson(u),a); build(rson(u),a);
		push_up(u);
	}
	void set(int u,int l,int r,int q,int k)
	{
		if(l == r){ tree[u].init(k); return;}
		int mid = (l+r)>>1;
		if(q<=mid) set(lson(u),q,k);
		else set(rson(u),q,k);
		push_up(u);
	}
	void dfs(int u,int l,int r)
	{
		printf("tree[%d]:\n",u);
		printf("seg = [%d, %d]\n",l,r);
		printf("sum = %lld, ans = %lld, rem = %lld\n",tree[u].sum,tree[u].ans,tree[u].rem);
		if(l == r) return;
		int mid = (l+r)>>1;
		dfs(lson(u)); dfs(rson(u));
	}
}tree;

int a[MAXN];

int main(void)
{
	int n,Q;
	scanf("%d%d",&n,&Q);
	for(int i=1; i<=n; ++i)
		scanf("%d",&a[i]);
	
	auto query = [&] (void)
	{
		static ll b[MAXN];
		fill(b+1, b+n+1, 0);
		for(int i=1; i<=n; ++i)
			b[i / 2 + 1] += a[i];
		
		ll cur = 0;
		for(int i=1; i<=n; ++i)
		{
			b[i] += b[i-1];
			cur = min(cur + a[i] / 2, b[i] / 3);
		}
		return cur;
	};
	
//	tree.build(1,1,n,a);
	
	printf("%lld\n",query());
	while(Q--)
	{
		int x,k;
		scanf("%d%d",&x,&k);
		a[x] += k;
		printf("%lld\n",query());
	}
	return 0;
}