#include <stdio.h>
void main()
{
	int x,p;
	scanf("%d",&x);
	if(x>=90)
	{
		p=x*3;
	}else if(x>=80&&x<90){
		p=x*2;
	}else if(x>=70&&x<80){
		p=x;
	}else{
		p=50;
	}
	printf("%d",p);
	  
}
/**************************************************************
	Problem: 1300
	User: admin
	Language: C
	Result: Accepted
	Time:18 ms
	Memory:1144 kb
****************************************************************/