#include <stdio.h>

int main() {
    int a, b,c;
    scanf("%d",&a);
    if(a%2==0)
    {
        b=a/2;
        printf("%d",b);
    }
    else
    {
        c=3*a+1;
        printf("%d",c);    
    }
    
    return 0;
}