#!/usr/bin/Rscript
collatz <- function(n)
{
        if(n<2) return(1)
        if(n%%2==0)
                return(c(n, collatz(n/2)))
        else
                return(c(n, collatz(3*n+1)))
}

sliding_product <- function(x, width)
{
        return(mapply(function(shiftx) {prod(window(x,shiftx,shiftx+width-1))},
                1:(length(x)-width+1)))
}

for(i in commandArgs(TRUE))
        print(max(sliding_product(collatz(as.numeric(i)) %% 10, 5)))