/**
* author: wxhtzdy
* created: 03.07.2022 13:33:18
**/
#include <bits/stdc++.h>
using namespace std;
string to_string(string s) {
return '"' + s + '"';
}
string to_string(const char* s) {
return to_string((string) s);
}
string to_string(bool b) {
return (b ? "true" : "false");
}
template <typename A, typename B>
string to_string(pair<A, B> p) {
return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A>
string to_string(A v) {
bool first = true;
string res = "{";
for (const auto &x : v) {
if (!first) {
res += ", ";
}
first = false;
res += to_string(x);
}
res += "}";
return res;
}
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
cerr << " " << to_string(H);
debug_out(T...);
}
#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
struct Frac {
long long p, q;
};
bool operator < (Frac a, Frac b) {
return a.p * b.q < b.p * a.q;
}
struct Point {
int x, y;
};
int orientation(Point a, Point b, Point c) {
long long prod = (b.y - a.y) * 1LL * (c.x - b.x)
- (b.x - a.x) * 1LL * (c.y - b.y);
return (prod == 0 ? 0 : (prod > 0 ? 1 : -1));
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n, h;
cin >> n >> h;
vector<Point> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i].x >> a[i].y;
}
vector<Point> L(n);
{
vector<Point> hull(1, a[0]);
for (int i = 1; i < n; i++) {
while ((int) hull.size() > 1 && orientation(hull.rbegin()[1], hull.rbegin()[0], a[i]) == -1) {
hull.pop_back();
}
L[i] = hull.back();
hull.push_back(a[i]);
}
}
vector<Point> R(n);
{
vector<Point> hull(1, a[n - 1]);
for (int i = n - 2; i >= 0; i--) {
while ((int) hull.size() > 1 && orientation(a[i], hull.rbegin()[0], hull.rbegin()[1]) == -1) {
hull.pop_back();
}
R[i] = hull.back();
hull.push_back(a[i]);
}
}
for (int i = 2; i < n - 1; i += 2) {
debug(i, L[i].x, L[i].y);
debug(i, R[i].x, R[i].y);
}
vector<pair<Frac, Frac>> ev;
for (int i = 2; i < n - 1; i += 2) {
Frac fL, fR;
fL.p = a[i].x * 1LL * (L[i].y - a[i].y) + (h - a[i].y) * 1LL * (L[i].x - a[i].x);
fL.q = L[i].y - a[i].y;
fR.p = a[i].x * 1LL * (R[i].y - a[i].y) + (h - a[i].y) * 1LL * (R[i].x - a[i].x);
fR.q = R[i].y - a[i].y;
ev.emplace_back(fL, fR);
}
sort(ev.begin(), ev.end(), [&](pair<Frac, Frac> a, pair<Frac, Frac> b) {
return a.second < b.second;
});
Frac lst;
int ans = 0;
for (int i = 0; i < (int) ev.size(); i++) {
if (i == 0 || lst < ev[i].first) {
ans += 1;
lst = ev[i].second;
}
}
cout << ans << '\n';
return 0;
}
