func_code_string: #include <bits/stdc++.h>   using namespace std;   const int tinf = (int)1e9 + 7;   const long long inf = (long long)1e18 + 7;   const int N = 1e5 + 5;   long long n, x[10000], y[10000], ans;   int main() {     {       ios ::sync_with_stdio(false);       cin.tie(0);     }     cin >> n;     for (int i = 0; i < n; i++) cin >> x[i] >> y[i];     for (int i = 1; i < n - 1; i++)       if (y[i] > y[i - 1] && x[i + 1] < x[i])         ans++;       else if (y[i] < y[i - 1] && x[i + 1] > x[i])         ans++;       else if (x[i] > x[i - 1] && y[i + 1] > y[i])         ans++;       else if (x[i] < x[i - 1] && y[i + 1] < y[i])         ans++;     cout << ans;   }   