题解 | #自守数#

while True:
    try:
        
        a = int(input())
        res = 0
        
        for i in range(a+1):
            b =str(i * i)
            if b[len(b)-len(str(i)):len(b)] == str(i):#注意只有字符串i才能取长度
                res+=1
            
        print(res)
    except:
        break