代码：

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
const int N = 1e5+10;
const LL INF = 2e18;
LL len[N];

string s="DKER EPH VOS GOLNJ ER RKH HNG OI RKH UOPMGB CPH VOS FSQVB DLMM VOS QETH SQB";
string a="DKER EPH VOS GOLNJ UKLMH QHNGLNJ A";
string b="AB CPH VOS FSQVB DLMM VOS QHNG A";
string c="AB";
char f(int n,LL k){
    if(k > len[n])
        return '.';

        if(n == 0){
            return s[k-1];
        }else{
            if(k<=a.size()){
                return a[k-1];
            }
            k -= a.size();
            if(k <= len[n-1]){
                return f(n-1,k);
            }
            k -= len[n-1];
            if(k <= b.size()){
                return b[k-1];
            }
            k -= b.size();
            if(k <= len[n-1]){
                return f(n-1,k);
            }
            k -= len[n-1];
            return c[k-1];

    }
}
int main()
{

    len[0] = s.size();
    for(int i=1;i<N;i++){
        len[i]=len[i-1]*2+a.size()+b.size()+c.size();
        len[i] = min(len[i],INF);
    }
    int q;
    cin>>q;
    while(q--){
        int n;
        LL k;
        cin>>n>>k;
        cout<<f(n,k);
    }

    return 0;
}