if __name__ == '__main__':
    print('hello')

tmpStr = 'aa'
tmpStr = raw_input()

print(tmpStr)


tmpStr = raw_input()

sliceStart = tmpStr[: len(tmpStr)/2]
sliceEnd = tmpStr[len(tmpStr)/2 :]

print(sliceStart)
print(sliceEnd)

if (sliceStart == sliceEnd) :
    print('YES')
else :
    print('NO')