#include <cstdio>
int n,d[2][302];
void add(int a[],int b[])
{
    int tr=0,i=1;
    while((i<=b[0])||(tr>0)){
        tr+=a[i]+b[i];
        a[i]=tr%10;
        tr/=10;
        i++;
    }
    i--;
    if(i>a[0]) a[0]=i;
}
int main()
{
    freopen("nunta.in","r",stdin);
    freopen("nunta.out","w",stdout);
    scanf("%d",&n);
    d[0][0]=d[0][1]=d[1][0]=d[1][1]=1;
    for(int i=2;i<=n;i++)
        add(d[i&1],d[1-(i&1)]);
    for(int i=d[n&1][0];i>0;i--)
        fputc(d[n&1][i]+'0',stdout);
    return 0;
}