#include
using namespace std;
bool sieve[500000];
int main() {
sieve[0]=sieve[1]=1;
for(int i=2;ii<=500000;i++)
if(!sieve[i])
for(int j=ii;j<=500000;j+=i)
sieve[j]=1;
int n;
cin>>n;
int counter=1;
while(n && counter<=500000)
{
counter++;
if(!sieve[counter])
nā;
}
cout<<counter;
}