#!/usr/bin/python
# -*- coding: UTF-8 -*-

def subString(s, length):
    us = unicode(s, 'utf-8')
    gs = us.encode('gb2312')
    n = int(length)
    t = gs[:n]
    while True:
        try:
            unicode(t, 'gbk')
            break
        except:
            n -= 1
            t = gs[:n]
    return t.decode('gb2312')

print subString('中华人民共和国',4)