4X

#include<bits/stdc++.h>
using namespace std;
vector<char> xiao;
vector<char> da;
vector<char> shu;
vector<char> other;
int main(){
    string s; cin >> s;
    int l = s.size();
    for(int i = 0;i < l;i++){
        if(s[i] >= 'a' && s[i] <= 'z') xiao.push_back(s[i]);
        else if(s[i] >= 'A' && s[i] <= 'Z') da.push_back(s[i]);
        else if(s[i] >= '0' && s[i] <= '9') shu.push_back(s[i]);
        else other.push_back(s[i]);
    }
    sort(xiao.begin(),xiao.end());
    sort(da.begin(),da.end());
    sort(shu.begin(),shu.end());
    sort(other.begin(),other.end());
    for(int i = 0;i < xiao.size();i++) cout << xiao[i];
    for(int i = 0;i < da.size();i++) cout << da[i];
    for(int i = 0;i < shu.size();i++) cout << shu[i];
    for(int i = 0;i < other.size();i++) cout << other[i];
    return 0;
}