# 佛波纳契数列
while 1:
    try:

        m = int(input())
        if m>=3:
            f1 = 1
            f2 = 1
            for i in range(3,m+1):
                f3 = f1+f2
                f1 = f2
                f2 = f3
            print(f3)
        elif m==1 or m==2:
            print(1)
    except:
        break