#include
#include<bits/stdc++.h>
using namespace std;
void prime(int p[10000000],int n){
for(int i=3;i<=5000000;i+=2){
p[i] = 1;
}
for(int i=3;i<=5000000;i+=2){
if(p[i]==1){
for(int j=1*i;i<=5000000;j+=i){
if(p[j]==1){
p[j] = 0;
}
}
}
}
p[0] = p[1] = 0 ;
p[2] = 1;
int csum[5000000] = {0};
for(int i=1;i<=5000000;i++){
csum[i] = csum[i-1] +p[i];
}
for(int i=1;i<=5000000;i++){
if(csum[i]==n){
cout<<i<<endl;
break;
}
}
return;
}
int main(){
int n;
cin>>n;
int arr[10000000] = {0};
prime(arr,n);
return 0;
}
