#include <bits/stdc++.h>
using namespace std;
int main() {
    int n, q;
    cin >> n >> q;
    set<int> behind;
    int cnt = 0;
    for (int i = 0; i < q; ++i) {
        int x;
        cin >> x;
        int id = abs(x);
        if (x > 0) {
            // Anika overtakes id
            if (behind.count(id)) {
                // Already behind → must be a lap
                cnt++;
            } else {
                // First time putting this guy behind
                behind.insert(id);
            }
        } else {
            // Someone overtakes Anika → they are ahead now
            behind.erase(id);
        }
    }
    cout << cnt << '\n';
    return 0;
}
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