#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define X first
#define Y second
#define pb push_back
#define ALL(v) v.begin(), v.end()
#define SZ(a) ((int)a.size())
#ifdef bbq
#include <experimental/iterator>
#define safe cerr<<__PRETTY_FUNCTION__<<" line "<<__LINE__<<" safe\n"
#define debug(a...) debug_(#a, a)
#define orange(a...) orange_(#a, a)
void debug_(auto s, auto ...a) {
cerr << "\e[1;32m(" << s << ") = (";
int f = 0;
(..., (cerr << (f++ ? ", " : "") << a));
cerr << ")\e[0m\n";
}
void orange_(auto s, auto L, auto R) {
cerr << "\e[1;33m[" << s << "] = [";
using namespace experimental;
copy(L, R, make_ostream_joiner(cerr, ", "));
cerr << "]\e[0m\n";
}
#else
#define safe ((void)0)
#define debug(...) safe
#define orange(...) safe
#endif
int main() {
ios::sync_with_stdio(0), cin.tie(0);
int n, q;
cin >> n >> q;
set<int> front, back;
int ans = 0;
while (q--) {
int x;
cin >> x;
if (x > 0) {
if (front.find(x) != front.end()) {
for (int i : front)
back.insert(i);
front.clear();
front.insert(x);
++ans;
}
else if (back.find(x) != back.end())
back.erase(x), front.insert(x);
else
front.insert(x);
}
else {
x *= -1;
front.erase(x);
back.insert(x);
}
orange(ALL(front));
orange(ALL(back));
debug(ans);
}
cout << ans << "\n";
}
