题解 | #自守数#

while True:
    try:
        n = int(input())
        output=0
        for i in range(n+1):
            sq=i*i
            str_sq=str(sq)
            str_i =str(i)
            num = len(str_i)
            if str_i==str_sq[-num:]:
                output+=1
        print(output)
    except:
        break