#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
using namespace std;
typedef long long LL;
typedef pair<int,int> pii;
typedef vector<int> vi;
template<class T> inline T re(){
T N = 0; char c = getchar(); bool neg = 0;
for (; c < '0' || c > '9'; c = getchar()) neg |= c == '-';
for (; c >= '0' && c <= '9'; c = getchar())
N = (N<<3)+(N<<1) + c - '0';
return neg ? -N : N;
}
const int MX = 2e5;
int n, q;
int qs[MX + 10];
// unordered_set<int> in_front, behind, tmp;
int tot = 0;
int in_front[MX * 4 + 5], behind[MX * 4 + 5];
int lz_front[MX * 4 + 5], lz_behind[MX * 4 + 5];
void build(int* st, int* lz, int p = 1, int l = 0, int r = n - 1) {
if (l == r) {
st[p] = 0, lz[p] = -1;
} else {
int md = (l + r) >> 1;
build(st, lz, p << 1, l, md);
build(st, lz, p << 1 | 1, md + 1, r);
st[p] = 0, lz[p] = -1;
}
}
void prop(int* st, int* lz, int p, int l, int r) { // set values
if (lz[p] == -1) return;
st[p] = lz[p];
if (l < r) {
lz[p << 1] = lz[p];
lz[p << 1 | 1] = lz[p];
}
lz[p] = -1;
}
void upd_set(int i, int j, int x, int* st, int* lz, int p = 1, int l = 0, int r = n - 1){
prop(st, lz, p, l, r);
if (j < l || i > r) return;
if (i <= l && j >= r) {
lz[p] = x;
prop(st, lz, p, l, r);
} else {
int md = (l + r) >> 1;
upd_set(i, j, x, st, lz, p << 1, l, md);
upd_set(i, j, x, st, lz, p << 1 | 1, md + 1, r);
st[p] = x;
}
}
int get(int pos, int* st, int* lz, int p = 1, int l = 0, int r = n - 1) {
prop(st, lz, p, l, r);
if (l == r) {
return st[p];
}
int md = (l + r) >> 1;
if (pos <= md) return get(pos, st, lz, p << 1, l, md);
else return get(pos, st, lz, p << 1 | 1, md + 1, r);
}
int main() {
n = re<int>(); q = re<int>();
for (int i = 1; i <= q; i++) qs[i] = re<int>();
build(in_front, lz_front);
build(behind, lz_behind);
upd_set(1, n - 1, 1, in_front, lz_front);
// for (int i = 1; i < n; i++) {
//in_front.insert(i);
// }
for (int i = 1; i <= q; i++) {
//cerr << "QS :: " << qs[i] << '\n';
if (qs[i] > 0) {
if (get(qs[i], in_front, lz_front) == 1) {
//cerr << "Case 1\n";
/* same lap */
upd_set(qs[i], qs[i], 0, in_front, lz_front);
upd_set(qs[i], qs[i], 1, behind, lz_behind);
} else {
//cerr << "Case 2\n";
/* already behind - overtake
* move all behind to in front
*/
upd_set(1, n - 1, 0, behind, lz_behind);
upd_set(qs[i], qs[i], 1, behind, lz_behind);
upd_set(1, n - 1, 1, in_front, lz_front);
upd_set(qs[i], qs[i], 0, in_front, lz_front);
tot++;
}
//if (in_front.find(qs[i]) != in_front.end()) {
// /* same lap */
// // in_front.erase(in_front.find(qs[i]));
// // behind.insert(qs[i]);
//} else {
//}
} else {
if (get(-qs[i], behind, lz_behind) == 1) {
//cerr << "Case 3\n";
upd_set(-qs[i], -qs[i], 0, behind, lz_behind);
upd_set(-qs[i], -qs[i], 1, in_front, lz_front);
} else {
//cerr << "Case 4\n";
}
//if (behind.find(qs[i]) != behind.end()) {
// /* same lap */
// // behind.erase(behind.find(qs[i]));
// // in_front.insert(qs[i]);
//} else {
// /* get lapped - do nothing */
//}
}
//cerr<< "front: "; for (int j = 1; j < n; j++) //cerr << get(j, in_front, lz_front) << " \n"[j + 1 == n];
//cerr << "back: "; for (int j = 1; j < n; j++) //cerr << get(j, behind, lz_behind) << " \n"[j + 1 == n];
//cerr << "tot: " << tot << '\n';
}
printf("%d\n", tot);
return 0;
}
