package main

import (
    "fmt"
)

func countWay(n int) int {
    if n ==1 {
        return 1
    }
    if n == 2 {
        return 2
    }
    return countWay(n-1) + countWay(n-2)
}

func main() {
    n := 0
    fmt.Scan(&n)
    fmt.Print(countWay(n))
}