#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <set>
#include <map>
#define INF 1e9
using namespace std;
typedef long long ll;
const ll MAXN = 100005;
void solve()
{
int n, q; cin >> n >> q;
set<int>v;
int ans = 0;
while (q--) {
int x; cin >> x;
if (x < 0) v.erase(-x);
else {
if (v.count(x)) {
++ans;
v.clear();
v.insert(x);
}
else v.insert(x);
}
}
cout << ans << "\n";
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int t = 1;// cin>>t;
while (t--) solve();
return 0;
}
