// Powered by CP Editor (https://cpeditor.org)
#include<bits/stdc++.h>
#define pb push_back
#define int long long
#define vi vector<int>
#define vvi vector<vector<int>>
#define vll vector<long long int>
#define vvll vector<vector<long long int>>
#define pii pair<int, int>
#define vpii vector<pair<int, int>>
#define vc vector<char>
#define vvc vector<vector<char>>
#define vb vector<bool>
#define mii map<int,int>
#define mll map<long long int, long long int>
#define mivi map<int,vector<int>>
#define f0r(i,n) for(int i=0;i<n;i++)
#define FOR(i,k,n) for(int i=k;i<n;i++)
using namespace std;
signed main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
//ifstream cin(".in");
//ofstream cout(".out");
int n;
cin>>n;
int q;
cin>>q;
//vi fb(n, -1);
//vi ans(n, 0);
int ans = 0;
set<int>s;
while(q--){
int x;
cin>>x;
if(x < 0){
s.erase(-x);
}
else{
if(s.count(x)){
ans++;
s = set<int>();
}
s.insert(x);
}
}
cout<<ans;
}
