#include <bits/stdc++.h>
using namespace std;
#define int long long
#define double long double
const double EPS = 1e-9;
int n, h;
struct point {
int x, y;
};
struct hull {
deque<point> dq;
int dir;
int getdir(point a, point b, point c) {
int tmp = a.x*(b.y-c.y) + b.x*(c.y-a.y) + c.x*(a.y-b.y);
if(tmp > 0) return 0;
else if(tmp < 0) return 1;
else return 2;
}
void insert(point x) {
while(dq.size() > 1) {
int s = dq.size();
if(getdir(dq[s-2], dq[s-1], x) != dir) dq.pop_back();
else break;
}
dq.push_back(x);
}
double query(point x) {
while(dq.size() > 1) {
int s = dq.size();
if(getdir(dq[s-2], dq[s-1], x) != dir) dq.pop_back();
else break;
}
point a = dq.back();
return (h-x.y)*1.0*(a.x-x.x)/(a.y-x.y)+x.x;
}
};
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int ans = 0, idx;
double last = -1e18;
cin >> n >> h;
point pt[n];
pair<double, double> pos[n/2-1];
idx = n/2-2;
for(int i = 0; i < n; i++) cin >> pt[i].x >> pt[i].y;
hull left, right;
left.dir = 0, right.dir = 1;
for(int i = n-2; i >= 3; i -= 2) {
left.insert(pt[i]);
pos[idx].first = left.query(pt[i-1]);
idx--;
}
idx = 0;
for(int i = 1; i < n-2; i += 2) {
right.insert(pt[i]);
pos[idx].second = right.query(pt[i+1]);
idx++;
}
sort(pos, pos+n/2-1);
for(int i = 0; i < n/2-1; i++) {
if(pos[i].second > last+EPS) {
ans++;
last = pos[i].first;
}
}
cout << ans;
}
