题解 | #自守数#

while True:
try:
n=int(input())
x=[]
xi=[]
res=0
for i in range(0,n+1):
x=list(map(int,str(i**2)))
xi=list(map(int,str(i)))
L=len(xi)
if x[-L:]==xi:
res+=1
print(res)
except:
break