# Aizu Problem ALDS_1_10_A: Fibonacci Number
#
import sys, math, os

# read input:
PYDEV = os.environ.get('PYDEV')
if PYDEV=="True":
    sys.stdin = open("sample-input.txt", "rt")


n = int(input())
if n < 2:
    print(1)
else:
    a, b = 1, 1
    for k in range(n - 1):
        a, b = b, a + b
    print(b) import sys, math, os sys math os PYDEV = os.environ.get('PYDEV') PYDEV os.environ.get('PYDEV') os.environ.get os.environ os environ get 'PYDEV' if PYDEV=="True":
    sys.stdin = open("sample-input.txt", "rt") PYDEV=="True" PYDEV "True" sys.stdin = open("sample-input.txt", "rt") sys.stdin sys stdin open("sample-input.txt", "rt") open "sample-input.txt" "rt" n = int(input()) n int(input()) int input() input if n < 2:
    print(1)
else:
    a, b = 1, 1
    for k in range(n - 1):
        a, b = b, a + b
    print(b) n < 2 n 2 print(1) print 1 a, b = 1, 1 a 1 b 1 for k in range(n - 1):
        a, b = b, a + b
     k range(n - 1) range n - 1 n 1 a, b = b, a + b a b b a + b a b print(b) print b a, b = b, a + b b a n = int(input()) int(input()) n a, b = 1, 1 1 a b = b, a + b a + b b b = 1, 1 1 b PYDEV = os.environ.get('PYDEV') os.environ.get('PYDEV') PYDEV
# Aizu Problem ALDS_1_10_A: Fibonacci Number
#
import sys, math, os

# read input:
PYDEV = os.environ.get('PYDEV')
if PYDEV=="True":
    sys.stdin = open("sample-input.txt", "rt")


n = int(input())
if n < 2:
    print(1)
else:
    a, b = 1, 1
    for k in range(n - 1):
        a, b = b, a + b
    print(b)