#include<stdio.h>
#include<stdlib.h>
int main ()
{
int x,y,n,a,b,c;
scanf("%d,&n");
while(c<n)
{
y=2;
c=1;
for(a=2;a<=y;a++)
{
b=0;
if(y%a==0)
{
b++;
}
}
y++;
if(b==0)
c++;
}
printf("%d",y-1);
return 0;
}