#include<bits/stdc++.h> using namespace std; int main(){ int n, q, cnt = 0; cin >> n >> q; map < int , int > is; for(int _ = 0; _ < q; _++){ int x; cin >> x; if(x >= 0){ if(is[x] == cnt)cnt++; is[x] = cnt; } else { is[abs(x)] = max(is[abs(x)] - 1, 0); } } cout << cnt - 1 << "\n"; }