#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pr;
const ll inf = 1e18;
int n, m, fa[200005], is[200005];
char ans[200005];
vector<int> g[200005];
deque<int> my[200005];
void dfs(int x) {
	if (is[x]) my[x].push_back(-1);
	for (int y : g[x]) {
		dfs(y);
	}
	sort(g[x].begin(), g[x].end(), [](int x, int y) {
		for (int i = 0; i < my[x].size() && i < my[y].size(); i++) {
			if (my[x][i] != my[y][i]) return my[x][i] < my[y][i];
		}
		if (my[x].size() != my[y].size()) return my[x].size() > my[y].size();
		return x < y;
	});
	int cur = 0;
	for (int y : g[x]) {
		my[x].push_back(0);
		if (my[x].size() > my[y].size()) {
			for (int t : my[y]) my[x].push_back(t);
			my[y].clear(), my[y].shrink_to_fit();
		} else {
			reverse(my[x].begin(), my[x].end());
			for (int t : my[x]) my[y].push_front(t);
			my[x].clear(), my[x].shrink_to_fit();
			swap(my[x], my[y]);
		}
		my[x].push_back(1);
		ans[y] = cur + 'a';
		cur++;
	}
}
void Solve() {
	scanf("%d%d", &n, &m);
	for (int i = 1; i <= n; i++) scanf("%d", &fa[i]), g[fa[i]].push_back(i);
	for (int i = 1, x; i <= m; i++) scanf("%d", &x), is[x] = 1;
	dfs(0);
	for (int i = 1; i <= n; i++) cout << ans[i];
	puts("");
	for (int i = 0; i <= n; i++) g[i].clear(), my[i].clear(), is[i] = 0;
}
int main() {
	int t;
	scanf("%d", &t);
	while (t--) Solve();
}