#include <bits/stdc++.h>
#define endl '\n'
using namespace std;
#define ll long long
#define ld long double
#define pll pair<ll,ll>
#define pb push_back
ll T=1,n,nq,x,y,ind,t,dp[5000099][3],k,mx,rs=0,c,pr,lft,a[2000009];
string s;
//map<ll,ll>ma;
void slv()
{
cin>>n>>nq;
pr=0;lft=0;rs=0;
ll t2=0,t1=0;
set<ll>bf;
while(nq--)
{
cin>>x;
if(x<0)
{
x=abs(x);
bf.erase(x);
}
else
{
if(bf.count(x))
{
rs++;
bf.clear();
bf.insert(x);
}
else bf.insert(x);
}
}
cout<<rs<<endl;
}
int main() {
//freopen("feast.in", "r", stdin);
//freopen("feast.out", "w", stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
//cin>>T;
while(T--)
slv();
return 0;
}
