#include<bits/stdc++.h>
using namespace std;
int main()
{
	int a;
	cin>>a;
	if(a>=30) cout<<(50-2)*a;
	else cout<<50*a;
	return 0;
}	

#include<bits/stdc++.h> using namespce std; int n; int main() { cin>>n; if(n<30) cout<<n50; else cout<<n48; return 0; }