#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <sstream>
#include <vector>
#include <complex>
#include <ctime>
#include <stack>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> VI;
typedef vector< VI > VVI;
typedef pair<int, int> PII;
typedef vector<PII> VPII;

#define REP(i, n) for(int i = 0; i < (n); ++i)
#define RREP(i, n) for(int i = (n) - 1; i >= 0; --i)
#define FOR(i, x, y) for(int i = (x); i <= (y); ++i)
#define RFOR(i, x, y) for(int i = (x); i >= (y); --i)
#define SZ(a) (int)(a).size()
#define ALL(a) (a).begin(),(a).end()
#define SORT(a) sort(ALL(a))
#define CLEAR(x) memset(x, 0, sizeof x);
#define COPY(FROM, TO) memcpy(TO, FROM, sizeof TO);
#define UNIQUE(c) SORT(c),(c).resize(unique(ALL(c))-(c).begin())
#define pb push_back
#define mk make_pair
#define sqr(x) ((x)*(x))
#define X first
#define Y second
const long double PI = acos(-1.0);
const double EPS = 1E-9;
const int inf = (1e+9);
const int NMAX = 1e+4;
const int MOD = 1743;

ll t, n;
int main () {
  cin >> t;
  while (t--) {
    string s;
    ll maxx = 1ll;
    cin >> s >> n;
    ll p = SZ(s);
    ll cc = 0;
    while (maxx < n) {
      maxx *= p;
      cc++;
      if (maxx < n)
        n -= maxx;
    }
    maxx /= p;
    VI dig (cc);
    cc = 0;
    while (n >= 0 && maxx) {
      dig[cc++] = n / maxx;
      n -= (n / maxx) * maxx;
      maxx /= p;
    }
    REP (i, SZ(dig)) {
      if (i == SZ(dig) - 1 && dig[i])
        dig[i]--;
      cout << s[dig[i]];
    }
    cout << endl;
  }
}
/*
5
EHT 34
ABCEFKO 4296473
ACEHKMPRTU 4125383079316
CDEGHIKLOSUWY 8333092520403744490
ADEFHNOPSUVY 3365973428406169086
1
ADEFHNOPSUVY 3365973428406169086
ANDHOPESYOUHAVEFUN
*/