// Suzune, if you want to ascend to a higher class, struggle with every ounce of strenght you have.
#include <bits/stdc++.h>
using namespace std;
const int baza = (1<<18);
int n,q,x, d[2*baza], odp;
void push(int v) {
d[2*v] = max(d[2*v],d[v]), d[2*v+1] = max(d[2*v+1],d[v]), d[v] = 0;
}
int value(int i) {
int w = 0; i += baza;
while (i > 0)
w = max(w,d[i]), i >>= 1;
return w;
}
void ustaw(int i, int val) {
int v = 1;
for (int j = 17; j >= 0; j--)
push(v), v = ((i&(1<<j)) ? 2*v+1 : 2*v);
d[v] = val;
}
void reset(int l, int r) {
l += baza-1, r += baza+1;
while (l/2 != r/2) {
if ((l&1) == 0)
d[l+1] = 2;
if ((r&1) == 1)
d[r-1] = 2;
l >>= 1, r >>= 1;
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> q;
for (int i = 1; i < n; i++)
d[i+baza] = 1;
for (int i = 0; i < q; i++) {
cin >> x;
if (x > 0) {
if (value(x) > 0)
ustaw(x,0);
else
odp++, reset(0,x-1), reset(x+1,baza-1);
}
else
ustaw(-x,1);
}
cout << odp << endl;
return 0;
}
