#include <bits/stdc++.h>
#include <random>
using namespace std;
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize ("unroll-loops")
typedef unsigned long long ull;
#define speed ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define ll long long
#define ld long double
#define pll pair <ll, ll>
#define pb push_back
const ll DIM = 2e5+7;
const ll bsize = 450;
const ll INF = 1e9;
const ll mln = 1e6+7;
const ll maxn = 30;
const ll mod = 1e9+7;
const ld gold = ((1+sqrt(5))/2);
const ll max_val = 1LL<<40LL;
//ll n, m, w, nq, mx, val, x, y, k, v1, v2, cost, day, g, l, r, start, finish;
ll cnt[DIM], a[DIM], nextt[DIM], prevv[DIM];
string s, type;
void solve(){
ll n, q, x;
cin>>n>>q;
for(int i=1; i<=n; i++){
nextt[i] = 1;
prevv[i] = 0;
}
ll res = 0;
ll curr = 0;
for(int i=1; i<=q; i++){
cin>>x;
if(x < 0){
nextt[abs(x)] = 1;
prevv[abs(x)] = 0;
}
if(x > 0){
if(nextt[x] == 1){
nextt[x] = 0;
prevv[x] = curr;
continue;
}
if(prevv[x] == curr){
res++;
curr++;
nextt[x] = 0;
prevv[x] = curr;
continue;
}
nextt[x] = 0;
prevv[x] = 0;
}
}
cout<<res<<endl;
}
signed main(){
speed;
int test = 1;
//cin>>test;
while(test--){
solve();
}
return 0;
}
