package main

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

var f int
var x int

func main() {
    getArg()
    fib(f)
    fmt.Println(x)
}

func getArg() int {
    s := ""
    for _, arg := range os.Args[1:] {
        s += arg
    }
    f, _ := strconv.Atoi(s)
    return f
}

func fib(f int) int {
    x, y := 0, 1
    for i := 0; i < f; i++ {
        x, y = y, x+y
    }
    return x
}