import java.util.Scanner;
class Main {public static void main(String[] args) {Scanner sc=new Scanner(System.in);int time=sc.nextInt();sc.close();int wugui = 0;//乌龟里程int tuzi = 0;//兔子里程int tuzi_run=0;int tuzi_rest=0;int is_rest=0;//是否需要休息：1是 0否int i=0;while(i<time){i++;if(tuzi_run==10){if(wugui<tuzi){is_rest=1;//需要休息}tuzi_run=0;}wugui+=3;if(is_rest==1){tuzi_rest++;if(tuzi_rest==30){is_rest=0;tuzi_rest=0;}}else{tuzi_run++;tuzi+=9;}}