n = int(raw_input())
a = 1
b = 1
for i in range(n-1):
    tmp = a
    a = b
    b += tmp
print b n = int(raw_input()) n int(raw_input()) int raw_input() raw_input a = 1 a 1 b = 1 b 1 for i in range(n-1):
    tmp = a
    a = b
    b += tmp i range(n-1) range n-1 n 1 tmp = a tmp a a = b a b b += tmp b tmp print b = 1 1 b a = b b a b += tmp tmp b n = int(raw_input()) int(raw_input()) n tmp = a a tmp a = 1 1 a
n = int(raw_input())
a = 1
b = 1
for i in range(n-1):
    tmp = a
    a = b
    b += tmp
print b