while True: try: n = int(input()) times = 2 for i in range(2,n+1): flag = 0 temp1 = i temp2 = i**2 while True: if(temp1 % 10 == temp2 % 10): temp1 = temp1 // 10 temp2 = temp2 // 10 flag = 1 else: flag = 0 break if(temp1 == 0 or temp2 == 0): break if(flag == 1): times += 1 print(times) except: break