#include<stdio.h>
int main()
{
int n;
int a,b,x,i;//variable for fibbo
int c,pos,j,z;//variable for prime
scanf("%d",&n);//enter position
if(n%2!=0)//if position is odd then calculate fibbo
{
a=1;
b=1;
if(n==1||n==3)
{
printf("%d",a);
}
else
{
for(i=2;i<(n/2+1);i++)
{
x=a+b;
a=b;
b=x;
}
printf("%d",x);
}
}
else//if position is even then calculate prime
{
pos=n/2;//for prime position
z=1;
for(i=1;i<100;i++)
{
c=0;
for(j=1;j<=i;j++)
{
if(i%j==0)
{
c=c+1;
}
}
if(c==2)
{
if(z++==pos)
{
printf("%d",i);
break;
}
}
}
}
return 0;
}