#include<bits/stdc++.h>
#include<ctime> 
using namespace std;
long long t;
long long n,k,a,b;
unsigned long long anger;
unsigned long long last,dis,num;
string music;
pair<string,int>f[100010];
pair<string,int> make_pair(string a,int b)
{
	pair<string,int>p;
	p.first=a,p.second=b;
	return p;
}
int main()
{
	cin>>t;
	while(t--)
	{
		cin>>n>>k>>a>>b;
		music='A';
		for(int i=1;i<n;i++)music+=char((music[i-1]-64)%58+65);
		anger=(n+1-k)*b;
		if(anger<=0)
		{
			anger=0;
			cout<<anger<<endl<<music<<endl;
			continue;
		}
	    num=n/(k-1);	
	    anger=(num)*a;
		for(int i=0;i<n;i++)
		    if((i+1)%(k-1)==0)music[i+1]=music[i];
        last=num*(k-1)-k+1;
        dis=n-last;
        if((dis-k+1)*b<a)
        {
            anger=anger-a+(dis-k+1)*b;
            music[num*(k-1)]=char(music[num*(k-1)]+1);
        }
		cout<<anger<<endl;
		cout<<music<<endl;	
	}
	return 0;
} 

不要在意什么f什么makepair什么的 那是dp的遗址（

checker返回的也不是什么score= type= 他返回一个什么

Wrong Answer.wrong output format Expected int64, but "18446744073369453871" found