def main():
#code here
arr=[]
s=[]
for i in range(10):
arr.append(i)
for i in range(11,1000):
i=str(i)
if i[0]==i[-1]:
arr.append(int(i))
N=int(input())
for i in arr:
if i<N:
s.append(i)
print("{}".format(s[-1]))
pass
if __name__ == '__main__':
main();
每日一练?