#include <cstdio>
FILE*si=fopen("nunta.in","r");
FILE*so=fopen("nunta.out","w");
char a[210],b[210];
int main()
{
    int n,k;
    short x,t;
    fscanf(si,"%i",&n);
    a[0]=b[0]=1;
    k=0;
    short nr;
    for(int i=2;i<=n;++i)
    {
        t=0;
        for(int j=0;j<=k;j++)
        {
            nr=b[j];
            x=a[j]+b[j]+t;
            b[j]=x%10;
            t=x/10;
            a[j]=nr;
        }
        if(t>0)
        {
            ++k;
            b[k]=t;
        }
    }
    if(n==1)
        fprintf(so,"%i",1);
    else
        for(int i=k;i>=0;--i)
        {
            fprintf(so,"%c",b[i]+'0');
        }
    return 0;
}