#include<bits/stdc++.h>
using namespace std;
#define Study ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define ll long long
#define ull unsigned long long
#define pb push_back
#define ff first
#define ss second
#define ins insert
#define all(x) x.begin(),x.end()
#define fori(x,y,z) for(ll x=y;x<=z;x++)
const ll INF=1e9;
const ll sz=2e5;
const ll mod=1e9+7;
vector<ll>Graph[sz+10];
vector<ll>removed(sz+10,0);
vector<ll>subs(sz+10,0);
void work(){
ll n;
cin>>n;
ll q;
cin>>q;
vector<bool>idk(n+10,0);
ll cnt=0;
ll ind=0;
while(q--){
ll x;
cin>>x;
if(x<0){
x=abs(x);
idk[x]=0;
}
else if(x>0){
//cout<<ind<<endl;
if(idk[x]){
cnt++;
idk.assign(n+10,0);
}
idk[x]=1;
}
//ind++;
}
cout<<cnt;
}
int main(){
Study;
ll t=1;
//cin>>t;
while(t--){
work();
}
}
