#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll
typedef pair<int,int> pi;
typedef pair<ll,ll> pill;
typedef vector <int> vi;
typedef vector <pi> vpi;
typedef pair<pi, ll> pii;
typedef set <ll> si;
typedef long double ld;
#define f first
#define s second
#define mp make_pair
#define FOR(i,s,e) for(int i=s;i<=int(e);++i)
#define DEC(i,s,e) for(int i=s;i>=int(e);--i)
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define lbd(x, y) lower_bound(all(x), y)
#define ubd(x, y) upper_bound(all(x), y)
#define aFOR(i,x) for (auto i: x)
#define mem(x,i) memset(x,i,sizeof x)
#define fast ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define INF (ll)1e18
#define MOD 998244353
typedef pair <vi, int> pvi;
typedef pair <int,pi> ipi;
typedef vector <pii> vpii;
typedef pair <pi,pi> pipi;
#define maxn 500010
int TC;
int N,Q,x,lap[maxn];
void solve(){
cin >> N >> Q;
int ans = 0;
unordered_set <int> before;
FOR(i,1,Q){
cin >> x;
if (x > 0){
if (before.find(x) != before.end()){
ans++;
before.clear();
before.insert(x);
}else before.insert(x);
}else before.erase(-x);
}
cout << ans << '\n';
}
int32_t main(){
fast;
//~ cin >> TC;
TC = 1;
while (TC--) solve();
}
