#include<bits/stdc++.h>
using namespace std;
const int N=2e5+5;
typedef long long ll;
int n,q,a[N],m,qx[N],qv[N],ct[N],c2,cq,id[N];
ll M,b[N],c[N],r[N],qc[N],qr[N],d[N],sd[N],ans[N],Ans,vr[N],a3[N];
int tr[N];
void upd(int x,int v){
	for(;x<=m;x+=(x&-x))tr[x]+=v;
}
int sum(int x){
	int res=0;
	for(;x;x-=x&-x)res+=tr[x];
	return res;
}
ll calc1(ll x){
	int p=lower_bound(d,d+n,x)-d;
	return x*p-(p?sd[p-1]:0)+sd[n-1]-(p?sd[p-1]:0)-x*(n-p);
}
void solve1(){
	for(int i=0;i<n;++i)d[i]=c[i];
	sort(d,d+n);
	for(int i=0;i<n;++i)sd[i]=d[i]+(i?sd[i-1]:0);
	for(int i=1;i<n;++i)Ans+=d[i]*i-sd[i-1];
	for(int i=1;i<=q;++i)if(~ans[i]){
		ans[i]+=Ans;
		ans[i]-=calc1(c[qx[i]]);
		ans[i]+=calc1(qc[i]);
		ans[i]-=abs(qc[i]-c[qx[i]]);
	}
}
vector<pair<int,int> >e[N];
void solve2(){
	Ans=0;
	for(int i=n-1;~i;--i){
		Ans+=sum(r[i]-1);
		upd(r[i],1);
	}
	for(int i=1;i<=q;++i)if(~ans[i]){
		ans[i]+=Ans;
		e[qx[i]].emplace_back(r[qx[i]],-i);
		e[qx[i]].emplace_back(qr[i],i);
	}
	memset(tr,0,sizeof(tr));
	for(int i=n-1;~i;--i){
		for(auto [x,z]:e[i]){
			int v=sum(x-1);
			if(z<0)ans[-z]-=v;
			else ans[z]+=v;
		}
		upd(r[i],1);
	}
	memset(tr,0,sizeof(tr));
	for(int i=0;i<n;++i){
		for(auto [x,z]:e[i]){
			int v=i-sum(x);
			if(z<0)ans[-z]-=v;
			else ans[z]+=v;
		}
		upd(r[i],1);
	}
	memset(tr,0,sizeof(tr));
}
struct qry{
	int x;ll y;int z,id;
	bool operator <(const qry a)const{return x<a.x;}
}Q[N];
bool cmp1(int x,int y){
	return c[x]<c[y];
}
bool cmp2(qry a,qry b){
	return a.y<b.y;
}
void cqd(int L,int R,int Ql,int Qr){
	if(L==R){
		sort(Q+Ql,Q+Qr+1,cmp2);
		return;
	}
	int mid=L+R>>1;
	int p=Ql,i,j;
	while(p<=Qr&&Q[p].x<=mid)++p;
	cqd(L,mid,Ql,p-1),cqd(mid+1,R,p,Qr);
	for(i=L,j=p;j<=Qr;++j){
		while(i<=mid&&c[id[i]]<Q[j].y)upd(r[id[i++]],1);
		a3[Q[j].id]+=i-L-sum(Q[j].z);
	}
	while((--i)>=L)upd(r[id[i]],-1);
	for(i=R,j=p-1;j>=Ql;--j){
		while(i>mid&&c[id[i]]>Q[j].y)upd(r[id[i--]],1);
		a3[Q[j].id]+=sum(Q[j].z-1); 
	}
	while((++i)<=R)upd(r[id[i]],-1); 
	inplace_merge(id+L,id+mid+1,id+R+1,cmp1);
	inplace_merge(Q+Ql,Q+p,Q+Qr+1,cmp2);
}
void solve3(){
	Ans=0;
	for(int i=0;i<n;++i)Q[++cq]={i,c[i],r[i],i+q+1},id[i]=i;
	for(int i=1;i<=q;++i)if(~ans[i])Q[++cq]={qx[i],qc[i],qr[i],i};
	sort(Q+1,Q+cq+1);
	cqd(0,n-1,1,cq);
	for(int i=0;i<n;++i)Ans+=a3[i+q+1];
	for(int i=1;i<=q;++i)if(~ans[i]){
		ans[i]-=Ans;
		ans[i]+=a3[qx[i]+q+1]*2;
		ans[i]-=a3[i]*2;
	}
}
int main(){
	scanf("%d%d",&n,&q);
	for(int i=0;i<n;++i)scanf("%d",&a[i]);
	for(int i=1;i<=q;++i)scanf("%d%d",&qx[i],&qv[i]);
	for(int i=0;i<n;++i){
		b[i]=(i&1)?-a[i]:a[i];
		if(i)b[i]+=b[i-1];
	}
	M=b[n-1];
	if(M<0){
		M=-M;
		for(int i=0;i<n;++i)a[i]=-a[i],b[i]=-b[i];
		for(int i=1;i<=q;++i)qv[i]=-qv[i];
	}
	if(n&1||!M){
		while(q--)puts("-1");
		return 0;
	}
	for(int i=0;i<n;++i){
		c[i]=b[i]<0?-(-b[i]-1)/M-1:b[i]/M,r[i]=(b[i]%M+M)%M;
		vr[++m]=r[i];
	}
	for(int i=1,x,v;i<=q;++i){
		x=qx[i],v=qv[i];
		b[x]+=(x&1)?-v:v;
		qc[i]=b[x]<0?-(-b[x]-1)/M-1:b[x]/M,qr[i]=(b[x]%M+M)%M;
		vr[++m]=qr[i];
		b[x]-=(x&1)?-v:v;
	}
	sort(vr+1,vr+m+1);
	m=unique(vr+1,vr+m+1)-vr-1;
	for(int i=0;i<n;++i)r[i]=lower_bound(vr+1,vr+m+1,r[i])-vr,++ct[r[i]],c2+=(ct[r[i]]==2);
	for(int i=1;i<=q;++i){
		qr[i]=lower_bound(vr+1,vr+m+1,qr[i])-vr;
		c2-=(ct[r[qx[i]]]==2);
		--ct[r[qx[i]]];
		++ct[qr[i]];
		c2+=(ct[qr[i]]==2);
		if(c2)ans[i]=-1;
		c2-=(ct[qr[i]]==2);
		++ct[r[qx[i]]];
		--ct[qr[i]];
		c2+=(ct[r[qx[i]]]==2);
	}
	solve1();
	solve2();
	solve3();
	for(int i=1;i<=q;++i)printf("%lld\n",ans[i]);
	return 0;
}