#include<stdio.h>
#include<stdlib.h>
unsigned long k,i,q=1,n=3,a[1000000];
int main(){
    FILE*f=fopen("prim.in","rb"); fscanf(f,"%lu",&k); fclose(f);
    FILE*g=fopen("prim.out","wb");
    if(k>1){
        while(q<k){
			if(a[n]==0){
				for(i=2;i<k;i++) if(i*n<=k) a[i*n]=1;
				q++;
			}
			n+=2;
        }
        fprintf(g,"%lu",n);
    }
    else fprintf(g,"%d",9);
    fclose(g);
    return 0;
}