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