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