#include<fstream.h>
#include<string.h>
ifstream f("nunta.in");
ofstream g("nunta.out");
int a[2000],t,b[2000],i,c[2000],n;
int main(){
f>>n;
if(n<4)
 g<<n;
else {
a[0]=1;a[1]=1;
b[0]=1;b[1]=2;
c[0]=1;
n=n-2;
while(n!=0){
for(i=1;i<=a[0]||i<=b[0]||t;i++,t=t/10)
	 c[i]=(t+=a[i]+b[i])%10;
   c[0]=i-1;
memcpy(a, b, sizeof(b));
memcpy(b, c, sizeof(c));
n--;
}
}
for(i=c[0];i>=1;i--)
  g<<c[i];
return 0;
}