Go: package main

/*
フィボナッチ数列
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func fibWithMemo(n int, memo map[int]int) int {
	if n == 0 || n == 1 {
		return 1
	}
	if val, ok := memo[n]; ok {
		return val
	}
	memo[n] = fibWithMemo(n-1, memo) + fibWithMemo(n-2, memo)
	return memo[n]
}

func fib(n int) int {
	memo := make(map[int]int)
	return fibWithMemo(n, memo)
}

func main() {
	scanner := makeScanner(1024)
	n := eGetInt(scanner)
	fmt.Println(fib(n))
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}
func min(a []int) int {
	m := a[0]
	for _, v := range a {
		if v < m {
			m = v
		}
	}
	return m
}

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

Python: n = int(input())
fib = [1, 1]

for i in range(2, n+1):
    fib.append(fib[i-1] + fib[i-2])

print(fib.pop())

Python: n = int(input())
def fib(x):
    lst=[1,1]
    for i in range(x-1):
        z = len(lst)
        y = int(lst[z-2])+int(lst[z-1])
        lst.append(y)
    print(lst[x])
fib(n)

Python: n = int(input())
fib = [1]*45
for i in range(2,n+1):
  fib[i] = fib[i-1]+fib[i-2]
print(fib[n])

Python: def deco_fibo(func):
    answer_list = [1, 1] + [None] * 43
    def main_fibo(i):
        ans = answer_list[i]
        if ans:
            return ans
        ans = func(i)
        answer_list[i] = ans
        return ans
    return main_fibo

@deco_fibo
def fibo(num):
    return fibo(num - 1) + fibo(num - 2)


n = int(input())

print(fibo(n))

Python: memo = [0, 1]

def fib(n):
    if (n in memo):
        return memo[n]
    ans = fib(n-1) + fib(n-2)
    memo.append(ans)
    return ans

n = int(input())
print(fib(n))

Python: n=int(input())
if n==0 or n==1:
    print(1)
else:
    N=1
    m=1
    for i in range(n-1):
        M=N+m
        m=N
        N=M
    print(M)

Python: list=[1,1]
n=int(input())

t=0
sum=0
if n==0 or n==1:
    print(1)
else:
    for i in range(n):
        list.append(list[i]+list[i+1])
    print(list[n])

Python: import sys

n = int(sys.stdin.readline().strip())

fib = [0] * (n+1)
fib[0] = 1
fib[1] = 1

for i in range(2, n+1):
    fib[i] = fib[i-1] + fib[i-2]
print(fib[n])

Python: n = int(input())
fib = [0] * (n + 1)
fib[0] = 1
if n > 0: fib[1] = 1
for i in range(2, n+1):
    fib[i] = fib[i-1] + fib[i-2]
print(fib[n])

Python: def g(a,b,n):
    if n==0 or n==1: return a
    else: return g(a+b,a,n-1)
a,b=1,1
print(g(a,b,int(input())))

Python: # def fibb(n):
#     if n == 1 or n == 2:
#         return 1
#     else:
#         return fibb(n-1)+fibb(n-2)

n = int(input())
fibb = [0]*45
fibb[0:2] = [1,1]
for i in range(2,45):
    fibb[i] = fibb[i-1] + fibb[i-2]
print(fibb[n])

Python: def fib(n):
    if n == 0:
        return 1
    if n == 1:
        return 1
    if F[n] > 0:
        return F[n]
    F[n] = fib(n-1) + fib(n-2)
    return F[n]

n = int(input())
F = [0 for i in range(n+1)]
print(fib(n))

Python: def resolve():
    n = int(input())
    A = [1, 1]
    for i in range(1, 45):
        A.append(A[i - 1] + A[i])
    print(A[n])


resolve()

Python: import sys
input = sys.stdin.readline

n = int(input())
F = [1]*50
for i in range(2, n+1):
    F[i] = F[i-1] + F[i-2]

print(F[n])

Python: def fib(n, fib_table):
    if n == 0 or n == 1:
        return 1
    if fib_table[n] != None:
        return fib_table[n]
    fib_table[n] = fib(n-1, fib_table) + fib(n-2, fib_table)
    return fib_table[n]

n = int(input())
fib_table = [None]*(n+1)
fib_table[0] = 1
fib_table[1] = 1

print(fib(n, fib_table))

Python: memo = [1, 1]

def fib(n):
    if (n in memo):
        return memo[n]
    ans = fib(n-1) + fib(n-2)
    memo.append(ans)
    return ans

n = int(input())
print(fib(n))

Python: # -*- coding: utf-8 -*-
"""
Created on Fri May  4 20:13:10 2018
ALDS1_10_A
@author: maezawa
"""

fib_arr = [None for _ in range(45)]
fib_arr[0] = 1
fib_arr[1] = 1

def fib(n):
    if fib_arr[n] != None:
        return fib_arr[n]
    fib_arr[n] = fib(n-1)+fib(n-2)
    return fib_arr[n]
    
n = int(input())
print(fib(n))

Python: x=int(input())
if x == 0 or x == 1 : print("1")
else : 
    i=0
    b=1
    c=1
    while i<(x-1) :
        d=b+c
        c=b
        b=d
        i=i+1
        
    print(b)

Python: n = int(input())
f = [0]*(n+3)
f[0], f[1] = 1, 1
for i in range(2, n+1):
    f[i] = f[i-1]+f[i-2]
print(f[n])

Python: import sys
input = sys.stdin.readline

n = int(input())
F = [1]*50
for i in range(2, n+1):
    F[i] = F[i-1] + F[i-2]

print(F[n])

Python: N = int(input())
dp = [0]*(N+1)
dp[0] = 1
dp[1] = 1
for i in range(2, N+1):
    dp[i] = dp[i-1]+dp[i-2]
print(dp[-1])

Python: n=int(input())
a=1
b=1
i=0
while i<n:
  a, b=b, a+b
  i+=1
print(a)

Python: #!/usr/bin/python

n = int(input())

def fib(n):
    l = list()
    l.append(1)
    l.append(1)

    for i in range(2, n+1):
        l.append(l[i-1] + l[i-2])

    return l[-1]

print(fib(n))

Python: def fib(n):
    if n == 0 or n == 1:
        return 1
    return fib(n-1) + fib(n-2)

n = int(input())
print(fib(n))

Python: def fib(n):
  if n ==1 or n == 0:
    return 1
  else:
    return fib(n-1) + fib(n-2)
  
print(fib(int(input())))

Python: n = int(input())
F = [0] * 45

def fib(n) :
    if n == 0 or n == 1 :
        return 1
    else :
        if F[n] != 0 :
            return F[n]
        else :
            F[n] = fib(n - 1) + fib(n - 2)
            return F[n]
        
print(fib(n))

Python: n = int(input())

def fib(i):
    if i<=1:
        return 1
    
    else:
        a, b = 0, 1
        for i in range(n+1):
            c = b + a
            b = a
            a = c
        return c

print(fib(n))

Python: target = int(input()) + 1
fib = [0 for n in range(target + 1)]
for i in range(target + 1):
    if i == 0:
        continue
    elif i == 1:
        fib[i] = 1
    else:
        fib[i] = fib[i - 1] + fib[i - 2]
print(fib[target])

Python: # ???????¨?????????????????§£???
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def fibonacci(n):
    num1 = 1
    num2 = 1
    tmp = 1

    for i in range(1, n):
        tmp = num1 + num2
        num1 = num2
        num2 = tmp

    return tmp


if __name__ == '__main__':
    n = int(input())
    result = fibonacci(n)
    print(result)