#include<iostream>
using namespace std;

int main()
{
    int n,sum=0;
    cin>>n;
    if(n<50 && n>=30)
    {
        sum = (n-30)/10+4;
    }
    else if(n<30) sum = n/10;
    else if(n>=50)
    {
        int a = n/50;
        int b = n%50/30;
        sum= a*7+b*4+(n-a*50-b*30)/10;
    }
    cout<<sum;
    return 0;
}