#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
using namespace std;
using namespace __gnu_pbds;
#define g0(x) get<0>(x)
#define g1(x) get<1>(x)
#define g2(x) get<2>(x)
#define mt make_tuple
#define mp make_pair
#define pb push_back
#define int long long
#define f first
#define s second
#define pll pair<long long, long long>
#define iii tuple<int,int,int>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
signed main(){
int n,q;cin>>n>>q;
vector<pll> state(n, {1, 0});
int last=0, ans=0;
for(int i=0;i<q;i++){
int x;cin>>x;
if(x < 0){
x=-x;
state[x]={1, i};
}
else {
if(state[x].s < last){
state[x].f=1;
}
if(state[x].f == 0){
ans++;
last=i;
}
state[x]={0, i};
}
}
cout<<ans;
}
