#include<bits/stdc++.h>
using namespace std;
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define int long long
#define ordered_set tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update>
#define fall(i,a,b) for(int i=a;i<=b;i++)
#define rfall(i,a,b) for(int i=a;i>=b;i--)
#define pb push_back
#define sz(x) (int)x.size()
#define all(x) x.begin(),x.end()
const int MAXN=2e5+10;
int v[MAXN],q,n;
int32_t main(){
std::ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin>>n>>q;
fall(i,1,n-1) v[i]=-1;
int ans=0;
vector<int> queries(q);
for(auto &u:queries) cin>>u;
fall(i,0,q-1){
int r=i;
while(r!=q){
int x=queries[r];
if(x<0) v[-x]=max(0ll,v[-x]-1);
else{
if(v[x]==1){
ans++;
break;
}
v[x]=1;
}
r++;
}
fall(l,i,r-1){
int x=queries[l];
x=abs(x);
v[x]=0;
}
i=r-1;
}
cout<<ans<<"\n";
}
