#include <algorithm>
#include <cmath>
#include <cstring>
#include <iostream>
#include <iomanip>
#include <limits.h>
#include <set>
#include <string>
#include <queue>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include <deque>
#include <map>
#include <chrono>
#include <random>
#include <bitset>
#include <tuple>
#define SZ(x) int(x.size())
#define FR(i,a,b) for(int i=(a);i<(b);++i)
#define FOR(i,n) FR(i,0,n)
#define FAST ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define A first
#define B second
#define mp(a,b) make_pair(a,b)
typedef long long LL;
typedef long double LD;
typedef unsigned long long ULL;
typedef unsigned __int128 U128;
typedef __int128 I128;
typedef std::pair<int,int> PII;
typedef std::pair<LL,LL> PLL;
using namespace std;
signed main(){
FAST;
LL n,q; cin>>n>>q;
set<LL> b; //those behind
LL ans=0;
while (q--){
LL x; cin>>x;
LL id=abs(x);
if (x<0){
if (b.count(id)) b.erase(id);
}
else{
if (b.count(id)){
ans++;
b.clear();
b.insert(id);
}
else b.insert(id);
}
}
cout<<ans;
return 0;
}
