Input

The only line of input contains three integers a1, a2, a3 (1 ≤ a1, a2, a3 ≤ 20), separated by spaces.

Output

Output a single integer.

Examples

Input

2 3 2


Output

5


Input

13 14 1


Output

14


Input

14 5 9


Output

464


Input

17 18 3


Output

53

Source: codeforces | Difficulty: MEDIUM_HARD


Solutions:
f = [0] * 22
(f[0], f[1], idx) = [int(x) for x in input().split()]
for i in range(2, 22):
	f[i] = f[i - 1] + f[i - 2]
print(f[idx])


(a, s, n) = map(int, input().split())
for i in range(n):
	(a, s) = (s, a + s)
print(a)


(a, b, n) = map(int, input().split())
if n == 0:
	print(a)
else:
	for i in range(1, n):
		(a, b) = (b, a + b)
	print(b)


(a, b, n) = map(int, input().split())
for i in range(n):
	(a, b) = (b, a + b)
print(a)


(x, y, n) = map(int, input().split())
a = [0] * (n + 1)
a[0] = x
a[1] = y
for i in range(2, n + 1):
	a[i] = a[i - 2] + a[i - 1]
print(a[n])


(a1, a2, a3) = map(int, input().split())
s = []
s.append(a1)
s.append(a2)
for i in range(2, a3 + 1):
	j = 0
	j += s[i - 1] + s[i - 2]
	s.append(j)
print(s[-1])


from __future__ import division, print_function
import math
import os
import sys
from fractions import *
from sys import *
from io import BytesIO, IOBase
from itertools import *
from collections import *
if sys.version_info[0] < 3:
	from __builtin__ import xrange as range
	from future_builtins import ascii, filter, hex, map, oct, zip
BUFSIZE = 8192

class FastIO(IOBase):
	newlines = 0

	def __init__(self, file):
		self._fd = file.fileno()
		self.buffer = BytesIO()
		self.writable = 'x' in file.mode or 'r' not in file.mode
		self.write = self.buffer.write if self.writable else None

	def read(self):
		while True:
			b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
			if not b:
				break
			ptr = self.buffer.tell()
			(self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr))
		self.newlines = 0
		return self.buffer.read()

	def readline(self):
		while self.newlines == 0:
			b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
			self.newlines = b.count(b'\n') + (not b)
			ptr = self.buffer.tell()
			(self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr))
		self.newlines -= 1
		return self.buffer.readline()

	def flush(self):
		if self.writable:
			os.write(self._fd, self.buffer.getvalue())
			(self.buffer.truncate(0), self.buffer.seek(0))

class IOWrapper(IOBase):

	def __init__(self, file):
		self.buffer = FastIO(file)
		self.flush = self.buffer.flush
		self.writable = self.buffer.writable
		self.write = lambda s: self.buffer.write(s.encode('ascii'))
		self.read = lambda : self.buffer.read().decode('ascii')
		self.readline = lambda : self.buffer.readline().decode('ascii')

def print(*args, **kwargs):
	(sep, file) = (kwargs.pop('sep', ' '), kwargs.pop('file', sys.stdout))
	at_start = True
	for x in args:
		if not at_start:
			file.write(sep)
		file.write(str(x))
		at_start = False
	file.write(kwargs.pop('end', '\n'))
	if kwargs.pop('flush', False):
		file.flush()
if sys.version_info[0] < 3:
	(sys.stdin, sys.stdout) = (FastIO(sys.stdin), FastIO(sys.stdout))
else:
	(sys.stdin, sys.stdout) = (IOWrapper(sys.stdin), IOWrapper(sys.stdout))
input = lambda : sys.stdin.readline().rstrip('\r\n')

def inp():
	return sys.stdin.readline().rstrip('\r\n')

def out(var):
	sys.stdout.write(str(var))

def lis():
	return list(map(int, inp().split()))

def stringlis():
	return list(map(str, inp().split()))

def sep():
	return map(int, inp().split())

def strsep():
	return map(str, inp().split())

def fsep():
	return map(float, inp().split())

def inpu():
	return int(inp())

def regularbracket(t):
	p = 0
	for i in t:
		if i == '(':
			p += 1
		else:
			p -= 1
		if p < 0:
			return False
	else:
		if p > 0:
			return False
		else:
			return True

def binarySearchCount(arr, n, key):
	left = 0
	right = n - 1
	count = 0
	while left <= right:
		mid = int((right + left) / 2)
		if arr[mid] <= key:
			count = mid + 1
			left = mid + 1
		else:
			right = mid - 1
	return count

def reverse1(string):
	pp = ''
	for i in string[::-1]:
		pp += i
	if pp == string:
		return True
	return False

def reverse2(list1):
	l = []
	for i in list1[::-1]:
		l.append(i)
	if l == list1:
		return True
	return False

def mex(list1):
	p = max(list1) + 1
	for i in range(len(list1)):
		if list1[i] != i:
			p = i
			break
	return p

def sumofdigits(n):
	n = str(n)
	s1 = 0
	for i in n:
		s1 += int(i)
	return s1

def perfect_square(n):
	s = math.sqrt(n)
	if s == int(s):
		return True
	return False

def roman_number(x):
	if x > 15999:
		return
	value = [5000, 4000, 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]
	symbol = ['F', 'MF', 'M', 'CM', 'D', 'CD', 'C', 'XC', 'L', 'XL', 'X', 'IX', 'V', 'IV', 'I']
	roman = ''
	i = 0
	while x > 0:
		div = x // value[i]
		x = x % value[i]
		while div:
			roman += symbol[i]
			div -= 1
		i += 1
	return roman

def soretd(s):
	for i in range(1, len(s)):
		if s[i - 1] > s[i]:
			return False
	return True

def countRhombi(h, w):
	ct = 0
	for i in range(2, h + 1, 2):
		for j in range(2, w + 1, 2):
			ct += (h - i + 1) * (w - j + 1)
	return ct

def countrhombi2(h, w):
	return h * h // 4 * (w * w // 4)

def binpow(a, b):
	if b == 0:
		return 1
	else:
		res = binpow(a, b // 2)
	if b % 2 != 0:
		return res * res * a
	else:
		return res * res

def binpowmodulus(a, b, m):
	a %= m
	res = 1
	while b > 0:
		if b & 1:
			res = res * a % m
		a = a * a % m
		b >>= 1
	return res

def coprime_to_n(n):
	result = n
	i = 2
	while i * i <= n:
		if n % i == 0:
			while n % i == 0:
				n //= i
			result -= result // i
		i += 1
	if n > 1:
		result -= result // n
	return result

def prime(x):
	if x == 1:
		return False
	else:
		for i in range(2, int(math.sqrt(x)) + 1):
			if x % i == 0:
				return False
		else:
			return True

def luckynumwithequalnumberoffourandseven(x, n, a):
	if x >= n and str(x).count('4') == str(x).count('7'):
		a.append(x)
	elif x < 1000000000000.0:
		luckynumwithequalnumberoffourandseven(x * 10 + 4, n, a)
		luckynumwithequalnumberoffourandseven(x * 10 + 7, n, a)
	return a

def luckynuber(x, n, a):
	p = set(str(x))
	if len(p) <= 2:
		a.append(x)
	if x < n:
		luckynuber(x + 1, n, a)
	return a

def interact(type, x):
	if type == 'r':
		inp = input()
		return inp.strip()
	else:
		print(x, flush=True)

def findTrailingZeros(n):
	count = 0
	while n >= 5:
		n //= 5
		count += n
	return count

def mergeSort(arr):
	if len(arr) > 1:
		mid = len(arr) // 2
		L = arr[:mid]
		R = arr[mid:]
		mergeSort(L)
		mergeSort(R)
		i = j = k = 0
		while i < len(L) and j < len(R):
			if L[i] < R[j]:
				arr[k] = L[i]
				i += 1
			else:
				arr[k] = R[j]
				j += 1
			k += 1
		while i < len(L):
			arr[k] = L[i]
			i += 1
			k += 1
		while j < len(R):
			arr[k] = R[j]
			j += 1
			k += 1
res = set()

def solve(p, l, a, b, n):
	if p > n or l > 10:
		return
	if p > 0:
		res.add(p)
	solve(p * 10 + a, l + 1, a, b, n)
	solve(p * 10 + b, l + 1, a, b, n)

def subsetsUtil(A, subset, index, d):
	print(*subset)
	s = sum(subset)
	d.append(s)
	for i in range(index, len(A)):
		subset.append(A[i])
		subsetsUtil(A, subset, i + 1, d)
		subset.pop(-1)
	return d

def subsetSums(arr, l, r, d, sum=0):
	if l > r:
		d.append(sum)
		return
	subsetSums(arr, l + 1, r, d, sum + arr[l])
	subsetSums(arr, l + 1, r, d, sum)
	return d

def main():
	(a, s, n) = map(int, input().split())
	for i in range(n):
		(a, s) = (s, a + s)
	print(a)
main()


(a, b, c) = map(int, input().split())
exec('a, b = b, a + b;' * c)
print(a)


(a, b, c) = map(int, input().split())
fiblist = []
fiblist.append(a)
fiblist.append(b)
while len(fiblist) - 1 < c:
	for i in range(2, 22):
		x = fiblist[i - 1] + fiblist[i - 2]
		fiblist.append(x)
else:
	print(fiblist[c])


(F0, F1, n) = map(int, input().split())
if n == 0:
	print(F0)
else:
	Ans = F1
	for i in range(1, n):
		Ans = F0 + F1
		F0 = F1
		F1 = Ans
	print(Ans)


def sui(f, n):
	if n == 0:
		return f[0]
	elif n == 1:
		return f[1]
	else:
		return sui(f, n - 1) + sui(f, n - 2)
f = [*map(int, input().split())]
print(sui(f, f[2]))