#include <bits/stdc++.h>
using namespace std;
#define int long long
const int INF = 1e18;
const int MOD = 1e9+7;
const int MAXN = 2e5;
#define md ((lf+rg)/2)
#define lc (pos*2)
#define rc (pos*2+1)
int n, m;
bool segtree[4*MAXN+5];
int lazy[4*MAXN+5];
void mulaidarinol(){}
void propagate(int lf, int rg, int pos){
if(lf > rg) return ;
if(lazy[pos] == -1) return ;
segtree[pos] = lazy[pos];
if(lf < rg){
lazy[lc] = lazy[rc] = lazy[pos];
}
lazy[pos] = -1;
}
void build(int lf, int rg, int pos){
lazy[pos] = -1;
if(lf == rg){
segtree[pos] = 1;
return ;
}
build(lf, md, lc);
build(md + 1, rg, rc);
segtree[pos] = (segtree[lc] | segtree[rc]);
}
void update(int ul, int ur, bool val, int lf, int rg, int pos){
propagate(lf, rg, pos);
if(rg < ul || ur < lf) return ;
if(ul <= lf && rg <= ur){
lazy[pos] = val;
propagate(lf, rg, pos);
return ;
}
update(ul, ur, val, lf, md, lc);
update(ul, ur, val, md + 1, rg, rc);
segtree[pos] = (segtree[lc] | segtree[rc]);
}
bool query(int ql, int qr, int lf, int rg, int pos){
propagate(lf, rg, pos);
if(rg < ql || qr < lf) return 0;
if(ql <= lf && rg <= qr) return segtree[pos];
bool ret = (query(ql, qr, lf, md, lc) | query(ql, qr, md + 1, rg, rc));
return ret;
}
void solve(){
cin >> n;
n--;
build(1, n, 1);
int ans = 0;
cin >> m;
while(m--){
int evnt; cin >> evnt;
if(evnt > 0){
bool res = query(evnt, evnt, 1, n, 1);
if(res == 0){
ans++;
update(1, n, 1, 1, n, 1);
update(evnt, evnt, 0, 1, n, 1);
}else{
update(evnt, evnt, 0, 1, n, 1);
}
}else{
evnt = -evnt;
bool res = query(evnt, evnt, 1, n, 1);
if(res == 0){
update(evnt, evnt, 1, 1, n, 1);
}
}
}
cout << ans << endl;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int tc = 1;
// cin >> tc;
while(tc--){
// mulaidarinol();
solve();
}
return 0;
}
