n=int(input())
dp=[0]*(n+1)
dp[0]=1
dp[1]=1


def rec(x):
    if dp[x]>0:
        return dp[x]

    res=rec(x-1)+rec(x-2)
    dp[x]=res
    return dp[x]

print(rec(n))
 n=int(input()) n int(input()) int input() input dp=[0]*(n+1) dp [0]*(n+1) [0] 0 n+1 n 1 dp[0]=1 dp[0] dp 0 1 dp[1]=1 dp[1] dp 1 1 def rec(x):
    if dp[x]>0:
        return dp[x]

    res=rec(x-1)+rec(x-2)
    dp[x]=res
    return dp[x] rec if dp[x]>0:
        return dp[x]

     dp[x]>0 dp[x] dp x 0 return dp[x] dp[x] dp x res=rec(x-1)+rec(x-2) res rec(x-1)+rec(x-2) rec(x-1) rec x-1 x 1 rec(x-2) rec x-2 x 2 dp[x]=res dp[x] dp x res return dp[x] dp[x] dp x x x print(rec(n)) print rec(n) rec n def rec(x):
    if dp[x]>0:
        return dp[x]

    res=rec(x-1)+rec(x-2)
    dp[x]=res
    return dp[x] def rec(x):
    if dp[x]>0:
        return dp[x]

    res=rec(x-1)+rec(x-2)
    dp[x]=res
    return dp[x] rec n=int(input()) int(input()) n dp=[0]*(n+1) [0]*(n+1) dp
n=int(input())
dp=[0]*(n+1)
dp[0]=1
dp[1]=1


def rec(x):
    if dp[x]>0:
        return dp[x]

    res=rec(x-1)+rec(x-2)
    dp[x]=res
    return dp[x]

print(rec(n))

