#include<bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define pf push_front
#define LC k<<1
#define RC k<<1|1
#define IO cin.sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define all(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define rep(i, a, n) for (int i = a; i < n; i++)
#define repn(i, a, n) for (int i = a; i <= n; i++)
#define per(i, a, n) for (int i = (n) - 1; i >= a; i--)
#define pern(i, a, n) for (int i = n; i >= a; i--)

typedef long long LL;
typedef long double LD;
typedef unsigned long long ull;
typedef pair<int, int> PII;
typedef pair<int, LL> PIL;
typedef pair<LL, int> PLI;
typedef pair<double, double> PDD;
typedef pair<ull, ull> PUU;
typedef pair<LL, LL> PLL;

const int N = 210000;
const int M = 1100000;
const int mod = 1e9+7;
const int inf = (int)1e9;
const LL INF = 1e18;
const double eps = 1e-9;

mt19937_64 Rand((unsigned long long)new char);
#define rand Rand

int T, n, m, pp[N], col[N], dep[N], rk[N];
vector<int> g[N], f[N];
vector<PII> h[N]; 
int cmp(int x, int y) {
	int n = h[x].size(), m = h[y].size();
	rep(i, 0, min(n, m)) {
		if (h[x][i].fi != h[y][i].fi) return h[x][i].fi < h[y][i].fi;
	}
	return n > m;
}
void dfs(int x) {
	f[dep[x]].pb(x);
	for (auto y: g[x]) dep[y] = dep[x] + 1, dfs(y);
}
int main() {
	IO;
	cin >> T;
	while (T--) {
		cin >> n >> m;
		repn(i, 0, n) g[i].clear(), f[i].clear(), h[i].clear(), pp[i] = 0;
		repn(i, 1, n) {
			int x;
			cin >> x;
			g[x].pb(i);
		}
		repn(i, 1, m) {
			int x;
			cin >> x;
			pp[x] = 1;
		}
		dfs(0);
		pern(i, 0, n) {
			if (f[i].size() == 0) continue;
			for (auto x: f[i]) {
				for (auto y: g[x]) h[x].pb(mp(rk[y], y));
				if (pp[x]) h[x].pb(mp(-1, x));
				sort(all(h[x]));
				int cnt = 0;
				rep(j, 0, h[x].size()) if (h[x][j].se != x) col[h[x][j].se] = cnt++;
			}
			sort(all(f[i]), cmp);
			int cnt = 0;
			rk[f[i][0]] = 0;
			rep(j, 1, f[i].size()) {
				int res = cmp(f[i][j], f[i][j - 1]) + cmp(f[i][j - 1], f[i][j]);
				if (res == 0) rk[f[i][j]] = cnt;
				else rk[f[i][j]] = ++cnt;
			}
		}
		repn(i, 1, n) cout << (char)('a' + col[i]);
		cout << "\n";
	}
	return 0;
}