#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
const ll LOG = 31;
const ll MOD = 1000000007;
const ll inf = 1e17;
const ll B = 2305843009213693951;
#define db(x) cerr << #x << " = " << x << " | "
#define dbg(x) cerr << #x << " = " << x << "\n"
#define Algerian ios::sync_with_stdio(0);
#define OI cin.tie(NULL);
int main() {
Algerian OI
ll n, q;
cin >> n >> q;
vector<ll> a(q);
for (ll& x : a) cin >> x;
ll r = 0, reset = 0;
vector<ll> last(n, -2);
for (ll i = 0; i < q; i++) {
if (a[i] < 0) {
last[-a[i]] = -1;
} else {
if (last[a[i]] >= reset) {
r++;
reset = i;
last[a[i]] = i;
} else {
last[a[i]] = i;
}
}
}
cout << r << "\n";
return 0;
}
