#include <bits/stdc++.h>
#define ll long long
#define db double
#define ld long double
#define endl '\n'
#define eb emplace_back
#define em emplace
#define pb push_back
#define pf push_front
#define pp pop_back
#define fr first
#define sc second
#define sz size
using namespace std;
const ll md =1e9 + 7;
const ll mx = 1e9 ;
signed main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie() ;
ll n , q ;
cin >> n >> q ;
set<ll>s ; ll r = 0 ;
for(ll i =0; i < q ; i++) {
ll x ;
cin >>x ;
if(x <0) {x = -x ; s.erase(x) ;}
else {
if(s.count(x)) {r += 1 ;s.clear();}
s.insert(x) ;
}
}
cout << r << endl ;
return 0;
}
