#include <fstream>

using namespace std;
int n,i,k,m,t,a[220],b[220],c[220];
ifstream fin ("nunta.in");
ofstream fout ("nunta.out");

int main (){

    fin>>n;
    // fibonacci
    a[0] = a[1] = b[0] = b[1] = 1;
    for (k=1;k<n;k++){
        // adunare intre a si b;
        if (a[0] > b[0])
            m = a[0];
        else
            m = b[0];
        t = 0;
        for(i=1;i<=m;i++){
            c[i] = a[i]+b[i]+t;
            t = c[i]/10;
            c[i] %= 10;
        }
        c[0] = m;
        if (t != 0)
            c[++c[0]] = t;
        for (i=1;i<=b[0];i++)
            a[i] = b[i];
        a[0] = b[0];
        for (i=1;i<=c[0];i++)
            b[i] = c[i];
        b[0] = c[0];
    }

    for (i=c[0];i>=1;i--)
        fout<<c[i];

    return 0;
}