#include <bits/stdc++.h>
using namespace std;
#define forn(i,n) for(int i=0;i<int(n);i++)
#define forsn(i,s,n) for(int i=int(s);i<int(n);i++)
#define dforn(i,n) for(int i=int(n)-1;i>=0;i--)
#define dforsn(i,s,n) for(int i=int(n)-1;i>=int(s);i--)
#define fst first
#define snd second
#define pb push_back
#define eb emplace_back
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
typedef long long ll;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef pair<int,int> ii;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
int n,q;
cin>>n>>q;
vi lap(n,-1);
int curr_lap=0;
forn(_,q){
int x;
cin>>x;
if(x>0){
if(lap[x]==curr_lap){
curr_lap++;
}
lap[x]=curr_lap;
}else{
lap[-x]=curr_lap-1;
}
}
cout<<curr_lap<<'\n';
return 0;
}
