#include<iostream> #include<vector> #include<algorithm> using namespace std; int main() {  int n;  cin >> n;  vector<int> dp(n + 1, 0);  dp[4] = 1;  dp[9] = 1;  for (int i = 4; i <= n; ++i) {   if (dp[i] > 0) {    if (i + 4 <= n) {     if (dp[i + 4] == 0) dp[i + 4] = dp[i] + 1;     else dp[i + 4] = min(dp[i + 4], dp[i] + 1);    }    if (i + 9 <= n) {     if (dp[i + 9] == 0) dp[i + 9] = dp[i] + 1;     else dp[i + 9] = min(dp[i + 9], dp[i] + 1);    }   }  }  if (dp[n] == 0) cout << -1 << endl;  else cout << dp[n] << endl;  return 0; }