#include <fstream>

#define maxN 210

long n,i,s,d;
unsigned char C[2][maxN];

inline void addV(long d,long s){
    C[d][0] = std::max(C[d][0],C[s][0]);
    long i;
    for(i=1;i<=C[d][0];i++) C[d][i]+=C[s][i];
    for(i=1;i<=C[d][0];i++){
        C[d][i+1] += C[d][i]/10;
        C[d][i] %= 10;
    }
    if(C[d][C[d][0]+1]) C[d][0]++;
}

int main()
{
    std::ifstream fin("nunta.in");
    std::ofstream fout("nunta.out");

    fin >> n ; fin.close();
    C[0][0] = C[0][1] = 1;
    C[1][0] = C[1][1] = 1;
    for(i=2;i<maxN;i++) C[0][i]=C[1][i]=0;

    s=0;d=1;
    for(i=2;i<=n;i++){
        s^=1;d^=1;
        addV(d,s);
    }

    for(i=C[d][0];i;i--) fout  << 1*C[d][i];
    fout.close();

    return 0;
}