#include <bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i,a,b) for (int i = a; i <= b; i++)
#define per(i,a,b) for (int i = a; i >= b; i--)
#define pii pair<int,int>
#define pb push_back
#define fi first
#define se second
#define all(v) (v).begin(), (v).end()
#define endl '\n'
const int MAXN = 2e5+10;
const int INF = 1e18+10;
const int MOD = 1e9+7;
void solve() {
int n,q;cin >> n >> q;
int ans = 0;
set<int> st;
rep(i,1,q) {
int x; cin >> x;
if(x<0) {
st.erase(-x);
continue;
}
if (st.find(x) != st.end()) {
ans++;
st.clear();
}
st.insert(x);
}
cout << ans << endl;
}
int32_t main() {
ios_base::sync_with_stdio(0); cin.tie(nullptr);
int tt = 1;
//cin >> tt;
while (tt--) solve();
return 0;
}
