import sys for line in sys.stdin.readlines(): n = int(line) total = 0 for i in range(1, n+1): total += 3 * i - 1 print(total)
import sys for line in sys.stdin.readlines(): n = int(line) total = 0 for i in range(1, n+1): total += 3 * i - 1 print(total)