题解 | #自守数#

import sys

for line in sys.stdin:
    a = line.split()
    n = int(a[0])
    out = 0

    for i in range(n+1):
        if int(str(i**2)[-len(str(i)):]) == i:
            out += 1
    
    print(out)

字符串与整数相互转换。