题解 | #字符统计#

import sys

def do(sentence):
    # 统计
    d_c = dict()
    d_r = dict()
    for c in sentence:
        if c in d_c.keys():
            d_c[c] += 1
        else:
            d_c[c] = 1
    # 排序
    return ''.join(dict(sorted(d_c.items(), key=lambda x:(-x[1], ord(x[0])))).keys()) 
    

if __name__ == '__main__':
    sentence = sys.stdin.readline().strip()
    r = do(sentence)
    print(r)