#include<stdio.h>
#include<stdlib.h>
unsigned long k,i,q=1,n=3,a[1000000];
int main(){
    FILE*f=fopen("fractii.in","r"); fscanf(f,"%lu",&k); fclose(f);
    FILE*g=fopen("fractii.out","w");
    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);
    fclose(g);
    return 0;
}