#include <bits/stdc++.h>
using namespace std;
#define int long long
const int INF = 1e18;
const int MOD = 1e9+7;
const int MAXN = 2e5;
int n, m;
bool stat[MAXN+5];
void mulaidarinol(){}
void solve(){
cin >> n;
n--;
for(int i = 1; i <= n; i++) stat[i] = 1;
int ans = 0;
cin >> m;
while(m--){
int evnt; cin >> evnt;
if(evnt > 0){
if(stat[evnt] == 0){
ans++;
for(int i = 1; i <= n; i++){
if(i == evnt) continue;
stat[i] = 1;
}
}else{
stat[evnt] = 0;
}
}else{
evnt = -evnt;
if(stat[evnt] == 0){
stat[evnt] = 1;
}
}
// cerr << endl;
// cerr << evnt << " : ";
// for(int i = 1; i <= n; i++) cerr << stat[i] << ' ';
}
cerr << "=> ";
cout << ans << endl;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int tc = 1;
// cin >> tc;
while(tc--){
// mulaidarinol();
solve();
}
return 0;
}
