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

