#include <bits/stdc++.h>
#define pb push_back
#define SS ios_base::sync_with_stdio(0);cin.tie(nullptr);cout.tie(nullptr);
// #define int long long
#define all(v) v.begin(),v.end()
using namespace std;
const int N = 2e5 + 1, MX = 4e5 + 177, inf = 1e9 + 1, mod = 998244353;
void solve(){
int n, q;
cin >> n >> q;
int ans = 1;
vector<int> last(n + 1, 0ll);
for(int i = 1; i <= q; i++){
int x;
cin >> x;
if(x > 0){
ans += (last[x] == ans);
last[x] = ans;
}
else{
last[-x] = 0;
}
}
cout << ans - 1;
}
signed main(){
SS
// freopen("trains.in", "r", stdin);
// freopen("trains.out", "w", stdout);
int t = 1;
// cin >> t;
while(t--){
solve();
}
}
