import sys

n=input()
a,b = 0,1

for i in range(0,n):
    a,b = b,a+b;
print b import sys sys n=input() n input() input a,b = 0,1 a 0 b 1 for i in range(0,n):
    a,b = b,a+b; i range(0,n) range 0 n a,b = b,a+b a b b a+b a b print n=input() input() n a,b = b,a+b b a b = b,a+b a+b b a,b = 0,1 0 a b = 0,1 1 b
import sys

n=input()
a,b = 0,1

for i in range(0,n):
    a,b = b,a+b;
print b