#include <bits/stdc++.h> #pragma GCC optimize("O3") using namespace std; using ll = long long; int main() { int n,q; cin >> n >> q; vector<bool> ahead(n,true); vector<ll> lap(1,0); while(q--) { int x; cin >> x; if(x>0) { if(ahead[x]) { ahead[x] = false; } else { lap[0]++; ahead[x] = false; } } else { x = -x; if(ahead[x]) { ahead[x] = true; } else { ahead[x] = true; } } // cout << lap[0] << "\n"; } cout << lap[0]; return 0; }