class Fib():
    f = [1] * 50
    def fib(self, n):
        for i in range(2, n + 1):
            self.f[i] = self.f[i - 1] + self.f[i - 2]
        return(self.f[n])

x = Fib()
print(x.fib(int(input()))) class Fib():
    f = [1] * 50
    def fib(self, n):
        for i in range(2, n + 1):
            self.f[i] = self.f[i - 1] + self.f[i - 2]
        return(self.f[n]) Fib f = [1] * 50 f [1] * 50 [1] 1 50 def fib(self, n):
        for i in range(2, n + 1):
            self.f[i] = self.f[i - 1] + self.f[i - 2]
        return(self.f[n]) fib for i in range(2, n + 1):
            self.f[i] = self.f[i - 1] + self.f[i - 2]
         i range(2, n + 1) range 2 n + 1 n 1 self.f[i] = self.f[i - 1] + self.f[i - 2] self.f[i] self.f self f i self.f[i - 1] + self.f[i - 2] self.f[i - 1] self.f self f i - 1 i 1 self.f[i - 2] self.f self f i - 2 i 2 return(self.f[n]) self.f[n] self.f self f n self self n n x = Fib() x Fib() Fib print(x.fib(int(input()))) print x.fib(int(input())) x.fib x fib int(input()) int input() input class Fib():
    f = [1] * 50
    def fib(self, n):
        for i in range(2, n + 1):
            self.f[i] = self.f[i - 1] + self.f[i - 2]
        return(self.f[n]) class Fib():
    f = [1] * 50
    def fib(self, n):
        for i in range(2, n + 1):
            self.f[i] = self.f[i - 1] + self.f[i - 2]
        return(self.f[n]) Fib x = Fib() Fib() x
class Fib():
    f = [1] * 50
    def fib(self, n):
        for i in range(2, n + 1):
            self.f[i] = self.f[i - 1] + self.f[i - 2]
        return(self.f[n])

x = Fib()
print(x.fib(int(input())))