#include <iostream>
#include <fstream>

using namespace std;

ifstream f("nunta.in");
ofstream g("nunta.out");

const int MAXN = 215,
          BAZA = 10;

int n;
unsigned char F1[MAXN]= {1,1},
              F2[MAXN]= {1,2},
              *M1 = F1, *M2 = F2, *AX;

void sum(unsigned char A[],unsigned char B[])
{
    int T=0;
    if(A[0]<B[0])
        A[0]=B[0];
    for(int i=1; i<=A[0]; i++)
    {
        T+=A[i]+B[i];
        A[i]=T%BAZA;
        T/=BAZA;
    }
    if(T>0)
        A[++A[0]]=1;
}

int main()
{
    f>>n;
    if(n<=2)
        M2[1]=n;
    else
        for(int i=3;i<=n;i++)
        {
            sum(M1,M2);
            swap(M1,M2);
        }
    for(int i=M2[0];i>=1;i--)
        g<<M2[i]+'0';
    return 0;
}