#include <cstdio>
#define LMAX 220
unsigned char A[LMAX],B[LMAX];
int n,i,j,r=0,aux;
int main(){
    freopen("nunta.in","r",stdin);
    freopen("nunta.out","w",stdout);
    scanf("%d",&n);
    A[0]=A[1]=B[0]=B[1]=1;
    for(i=2;i<=n;++i){
        r=0;
        for(j=1;j<=B[0]||r;++j){
            r+=(A[j]+B[j]);
            aux=B[j];
            B[j]=r%10;
            A[j]=aux;
            r/=10;
        }
        A[0]=B[0];
        B[0]=j-1;
    }
    for(i=B[0];i;--i)
        printf("%d",B[i]);
    return 0;
}