package main

import (
        "os"
        "strconv"
        "fmt"
)

func fib(n int) int {
        if n <= 1 {
                return n
        } else {
                return fib(n-1) + fib(n-2)
        }
}

func main() {
        n,_ := strconv.Atoi(os.Args[1])
        fmt.Printf("%d\n", fib(n))
}