#include <fstream>
#include <string.h>
std::ifstream f("nunta.in");
std::ofstream g("nunta.out");
int a[1000],t,b[1000],i,c[1000],n;

int main()
{
    f>>n;
    if(n<4) {
        g<<n;
        return 0;
    }
    a[0]=1;a[1]=1;
    b[0]=1;b[1]=2;
    c[0]=1;
    n=n-2;
    while(n!=0){
        for(i=1;i<=a[0]||i<=b[0]||t;i++,t=t/10)
            c[i]=(t+=a[i]+b[i])%10;
        c[0]=i-1;
        memcpy(a,b,sizeof(b));
        memcpy(b,c,sizeof(c));
        n--;
    }
    for(i=c[0];i>=1;i--)
    g<<c[i];
    return 0;
}