rt，蒟蒻一枚

#include <bits/stdc++.h>
#define ll long long
#define endl '\n'

using namespace std;
const int E=1e6+5;
ll n;
ll cnt[E];
string arr[100];
bool cmp(ll a,ll b){
	return a>b;
}
ll cz(string a){
	ll sum=0;
	ll len=a.length();
	for(int i=0;i<len;i++){
		if(a[i]>='0' && a[i]<='9'){
			sum+=int(a[i]-'0');
		}
		else if(a[i]>='a' && a[i]<='z'){
			sum+=int(a[i]-'a'+10);
		}
		else if(a[i]>='A' && a[i]<='Z'){
			sum+=int(a[i]-'A'+10);
		}
		if(i<len-1){
			sum*=16;
		}
	}
	return sum;
}
string zc(ll a){
	string b;
	while(a){
		if(a%16<=9){
			b+=a%16+48;
		}
		else{
			b+=a%16+55;
		}
		a/=16;
	}
	return b;
}
int main(){
	cin >>n;
	for(int i=0;i<n;i++){
		cin >>arr[i];
	}
	for(int i=0;i<n;i++){
		ll len=arr[i].length();
		for(int j=0;j<len;j++){
			cnt[cz(arr[i])]++;
		}
	}
	stable_sort(cnt,cnt+256,cmp);
	ll cnt1=0;
	for(int i=0;i<256;i++){
		if(cnt[i]!=0 && cnt1<=30){
			cout <<zc(i);
		}
	}
	en:
    return 0;
}

哪里re了啊