def main():
    import sys
    N = int(sys.stdin.readline())
    L = [0 for i in range(45)]
    L[0], L[1] = 1, 1
    for i in range(2, 45):
        L[i] = L[i-1] + L[i-2]
    #print(L)
    print(L[N])
    



if __name__=='__main__':
    main() def main():
    import sys
    N = int(sys.stdin.readline())
    L = [0 for i in range(45)]
    L[0], L[1] = 1, 1
    for i in range(2, 45):
        L[i] = L[i-1] + L[i-2]
    #print(L)
    print(L[N])
     main import sys sys N = int(sys.stdin.readline()) N int(sys.stdin.readline()) int sys.stdin.readline() sys.stdin.readline sys.stdin sys stdin readline 0 for i in range(45) for i in range(45) i range(45) range 45 for i in range(45) 0 L = [0 for i in range(45)] L [0 for i in range(45)] L[0], L[1] = 1, 1 L[0] L 0 1 L[1] L 1 1 for i in range(2, 45):
        L[i] = L[i-1] + L[i-2]
    #print(L)
     i range(2, 45) range 2 45 L[i] = L[i-1] + L[i-2] L[i] L i L[i-1] + L[i-2] L[i-1] L i-1 i 1 L[i-2] L i-2 i 2 print(L[N]) print L[N] L N if __name__=='__main__':
    main() __name__=='__main__' __name__ '__main__' main() main def main():
    import sys
    N = int(sys.stdin.readline())
    L = [0 for i in range(45)]
    L[0], L[1] = 1, 1
    for i in range(2, 45):
        L[i] = L[i-1] + L[i-2]
    #print(L)
    print(L[N])
     def main():
    import sys
    N = int(sys.stdin.readline())
    L = [0 for i in range(45)]
    L[0], L[1] = 1, 1
    for i in range(2, 45):
        L[i] = L[i-1] + L[i-2]
    #print(L)
    print(L[N])
     main
def main():
    import sys
    N = int(sys.stdin.readline())
    L = [0 for i in range(45)]
    L[0], L[1] = 1, 1
    for i in range(2, 45):
        L[i] = L[i-1] + L[i-2]
    #print(L)
    print(L[N])
    



if __name__=='__main__':
    main()
