# include <cstdio>
using namespace std;
short int s[2][105];
short int a[2];
int n;
int main(void)
{
    freopen("nunta.in","r",stdin);
    freopen("nunta.out","w",stdout);
    scanf("%d",&n);
    a[0]=a[1]=s[0][1]=1;
    for (int i=1;i<=n;++i)
    {
        for (int j=1,l=(a[0] > a[1] ? a[0]:a[1]);j<=l;++j)
            s[i&1][j]=s[0][j]+s[1][j],s[i&1][j+1]+=s[i&1][j]/1000,s[i&1][j]%=1000;
        while (s[i&1][a[i&1]+1]) ++a[i&1],s[i&1][a[i&1]+1]+=s[i&1][a[i&1]]/1000,s[i&1][a[i&1]]%=1000;
    }
    printf("%d",(s[n&1][a[n&1]]));
    for (int i=a[n&1]-1;i;--i)
    {
        if (10<=s[n&1][i] && s[n&1][i]<=99) printf("0");
        if (0<=s[n&1][i] && s[n&1][i]<=9) printf("00");
        printf("%d",s[i]);
    }
    return 0;
}