#include <bits/stdc++.h>
using namespace std;
#define int long long
#define F first
#define S second
void dbg(vector<int> &v) { for(int k: v) cout << k << " "; }
void dbg(map<int, int> &v) { for(auto [a, b]: v) cout << a << " " << b << '\n'; }
void dbg(set<int> &v) { for(int k: v) cout << k << " "; }
struct DSU {
vector<int> par, sz;
DSU(int n) {
par.resize(n+1);
sz.resize(n+1, 1);
for(int i = 0 ; i <= n ; i++) par[i] = i;
}
int pfind(int v) {
if(v == par[v]) return v;
else return par[v] = pfind(par[v]);
}
void sunion(int a, int b) {
a = pfind(a);
b = pfind(b);
if(a == b) return;
if(sz[a] > sz[b]) swap(a, b);
par[b] = a;
sz[a] += sz[b];
}
};
const int MOD = 1e9 + 7;
using pr = array<int, 3>;
const int MX = 2e5 + 1;
void solve() {
int n, q; cin >> n >> q;
set<int> g;
int r = 0;
int f=0;
for(int i = 0 ; i < q ; i++) {
int x; cin >> x;
if(x > 0) {
if(g.contains(-x)) g.erase(-x);
else if(g.contains(x)) {
g.clear();
r++;
}
g.insert(x);
}
else {
// g.erase(-x);
g.insert(x);
}
}
cout << r;
}
signed main() {
// int t; cin >> t;
int t = 1;
while(t--) solve();
}
// think greedy first, Div2AB usually are some sort of greedy, super simple usually
// C on Div2 or E on Div3/4 require more thinking but still not too hard
// for later problems, think about data structures like segment tree and ordered set
// do smth instead of nothing and stay organized
// WRITE STUFF DOWN
// DON'T GET STUCK ON ONE APPROACH
