#include<stdio.h>
int a[200],b[200],c[200];
int plus(int a[200],int b[200])
{int i;
    for(i=1;i<=200;i++)
    a[i]+=b[i];
    for(i=1;i<=200;i++)
    if(a[i]>10)
    {a[i+1]+=a[i]/10;
    a[i]%=10;
}
if(a[1]==0)
for(i=1;i<=200;i++)
a[i]=a[i]+1;
}

int copy(int a[200],int b[200])
{int i;
for(i=1;i<=200;i++)
a[i]=b[i];}
int main ()
{
    freopen("nunta.in","r",stdin);
    freopen("nunta.out","w",stdout);
    int q,n,i,k;
    scanf("%d",&n);
    a[1]=1;
    b[1]=1;
    for(q=1;q<n;q++)
    {//c=a;
    copy(c,a);
    plus(a,b);
   // b=c;
   copy(b,c);
}int zr;
zr=0;
for(i=200;i>=1;i--)
{
                 if(a[i]!=0)
                 zr=1;
                 if(zr==1)
                 printf("%d",a[i]);
                 }
return 0;
}