#include <stdio.h>	

int main(void){	

	int Sum =0, i, n, end;		

	printf("Input number:");
	scanf("%d",&n);

	end = 2*n;

	for(i=1; i<=end; i=i+2) Sum = Sum+i;
	
	printf("Answer is %d.\n",Sum);

	return 0;

}