#include <bits/stdc++.h>
using namespace std;
/*<DEBUG>*/
#define tem template <typename
#define can_shift(_X_, ...) enable_if_t<sizeof test<_X_>(0) __VA_ARGS__ 8, debug&> operator<<(T i)
#define _op debug& operator<<
tem C > auto test(C *x) -> decltype(cerr << *x, 0LL);
tem C > char test(...);
tem C > struct itr{C begin, end; };
tem C > itr<C> get_range(C b, C e) { return itr<C>{b, e}; }
struct debug{
#ifdef _LOCAL
~debug(){ cerr << endl; }
tem T > can_shift(T, ==){ cerr << boolalpha << i; return *this; }
tem T> can_shift(T, !=){ return *this << get_range(begin(i), end(i)); }
tem T, typename U > _op (pair<T, U> i){
return *this << "< " << i.first << " , " << i.second << " >"; }
tem T> _op (itr<T> i){
*this << "{ ";
for(auto it = i.begin; it != i.end; it++){
*this << " , " + (it==i.begin?2:0) << *it;
}
return *this << " }";
}
#else
tem T> _op (const T&) { return *this; }
#endif
};
string _ARR_(int* arr, int sz){
string ret = "{ " + to_string(arr[0]);
for(int i = 1; i < sz; i++) ret += " , " + to_string(arr[i]);
ret += " }"; return ret;
}
#define exp(...) " [ " << #__VA_ARGS__ << " : " << (__VA_ARGS__) << " ]"
/*</DEBUG>*/
typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int uint;
typedef pair<int, int> pii;
typedef long double ld;
//mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
#define pb push_back
#define FAST ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define TC int __TC__; cin >> __TC__; while(__TC__--)
#define ar array
const int INF = 1e9 + 7, N = 1e6 + 1;
int vis[N];
struct point{
ll p1, p2;
int id;
bool start;
bool operator==(const point &a){
return p1*a.p2 == p2*a.p1;
}
bool operator!=(const point &a){
return p1*a.p2 != p2*a.p1;
}
};
struct r_point{
ll x, y;
r_point operator-(const r_point &a){
return {x - a.x, y - a.y};
}
};
int turn(r_point a, r_point b){
ll s = a.x*b.y - a.y*b.x;
return (s > 0) - (s < 0);
}
int turn(r_point a, r_point b, r_point c){
return turn(b-a, c-a);
}
vector<point> points;
r_point p[N];
int main(void)
{
FAST;
ll h;
int n; cin >> n >> h;
for(int i = 1; i <= n; ++i) cin >> p[i].x >> p[i].y;
int l;
ll lx, ly;
vector<r_point> hull;
for(int i = 3; i <= n-2; i+=2){
ll x = p[i].x, y = p[i].y;
while(hull.size() >= 2 && turn(p[i-1], hull.back(), hull[hull.size()-2]) <= 0) hull.pop_back();
hull.pb(p[i-1]);
if(hull.size() == 1 || turn(p[i], hull[1], hull[0]) <= 0) l = 0;
else{
l = hull.size() - 1;
for(int j = 22; j >= 0; --j){
if(l - (1<<j) > 0 && turn(p[i], hull[l-(1<<j)], hull[l - (1<<j) -1]) <= 0) l-=(1<<j);
}
if(turn(p[i], hull[l], hull[l-1]) <= 0) --l;
}
lx = hull[l].x;
ly = hull[l].y;
points.pb({(h - y)*(lx-x) + x*(ly-y), ly-y, i, 1});
}
hull.clear();
for(int i = n-2; i >= 3; i -= 2){
ll x = p[i].x, y = p[i].y;
while(hull.size() >= 2 && turn(p[i+1], hull.back(), hull[hull.size()-2]) >= 0) hull.pop_back();
hull.pb(p[i+1]);
if(hull.size() == 1 || turn(p[i], hull[1], hull[0]) >= 0) l = 0;
else{
l = hull.size() - 1;
for(int j = 22; j >= 0; --j){
if(l - (1<<j) > 0 && turn(p[i], hull[l-(1<<j)], hull[l - (1<<j) -1]) >= 0) l-=(1<<j);
}
if(turn(p[i], hull[l], hull[l-1]) >= 0) --l;
}
lx = hull[l].x;
ly = hull[l].y;
points.pb({(h-y)*(lx-x) + x*(ly-y), ly-y, i, 0});
}
auto cmp = [](const point &a, const point &b){
if(a.p1*b.p2==a.p2*b.p1) return a.id < b.id;
return a.p1*b.p2 < a.p2*b.p1;
};
sort(points.begin(), points.end(), cmp);
stack<int> cur;
int ans = 0;
bool clear = 0;
for(int i = 0; i < (int)points.size(); ++i){
if(clear && (i == (int)points.size()-1 || points[i] != points[i+1])){
clear = 0;
++ans;
vis[points[i].id] = 1;
while(cur.size()){
vis[cur.top()] = 1;
cur.pop();
}
continue;
}
if(points[i].start){
cur.push(points[i].id);
}else{
if(i < (int)points.size()-1 && !vis[points[i].id] && points[i] == points[i+1]) clear = 1;
if(clear) continue;
if(!vis[points[i].id]){
++ans;
vis[points[i].id] = 1;
while(cur.size()){
vis[cur.top()] = 1;
cur.pop();
}
}
}
}
cout << ans << '\n';
return 0;
}
