#include <bits/stdc++.h>

#define f first
#define s second
#define pb push_back
#define mp make_pair

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;

const int N = 200500, inf = 1e9, mod = 998244353;
const ll INF = 1e18;

int sum(int a, int b) {
    a += b;
    if (a >= mod)
        a -= mod;
    return a;
}

int sub(int a, int b) {
    a -= b;
    if (a < 0)
        a += mod;
    return a;
}

int mult(int a, int b) {
    return 1ll * a * b % mod;
}

int bp(int a, int b) {
    int res = 1;
    while (b) {
        if (b & 1)
            res = mult(res, a);
        a = mult(a, a);
        b >>= 1;
    }
    return res;
}

int inv(int x) {
    return bp(x, mod - 2);
}

vector<int> g[N];
int n, m, ans[N], sz[N];
bool key[N];
int h[N];

int k;
map<vector< int >, int> mt[2];


int kek(int v, int u) {
    //v better u => 1
    //v same u => 0
    //v worse u => -1

    if (h[v] == h[u])
        return 0;

    if (key[v] && !key[u])
        return 1;
    if (!key[v] && key[u])
        return -1;

    for (int i = 0; i < 26; i++) {
        if (i < g[v].size() && i < g[u].size()) {
            int res = kek(g[v][i], g[u][i]);
            if (res != 0)
                return res;
        }
        if (i < g[v].size() && i >= g[u].size()) {
            return 1;
        }
        if (i >= g[v].size() && i < g[u].size()) {
            return -1;
        }
    }
    return 0;
}

void dfs(int v) {
    sz[v] = key[v];
    for (auto to: g[v]) {
        dfs(to);
        sz[v] += sz[to];
    }
    sort(g[v].begin(), g[v].end(), [](int i, int j) {
        int res = kek(i, j);
        if (res == 0)
            return i < j;
        return (res == 1);
    });
    vector< int > a;
    for(auto to : g[v])
        a.pb(h[to]);
    if(mt[key[v]].find(a) == mt[key[v]].end())
        mt[key[v]][a] = k++;
    h[v] = mt[key[v]][a];

    for(int i = 0; i < g[v].size(); i++)
        ans[g[v][i]] = i;
}

void solve() {
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        int v;
        cin >> v;
        g[v].pb(i);
    }
    for (int i = 0; i < m; i++) {
        int v;
        cin >> v;
        key[v] = 1;
    }
    dfs(0);

    for (int i = 1; i <= n; i++)
        cout << (char) ('a' + ans[i]);
    cout << "\n";

    for (int i = 0; i <= n; i++) {
        int v = i;
        g[v].clear();
        key[v] = 0;
    }

}

int main() {
#ifdef DEBUG
    freopen("input.txt", "r", stdin);
#endif
    ios_base::sync_with_stdio(false);
    int t = 1;
    cin >> t;
    for (int i = 1; i <= t; i++) {
//        cout << "Case #" << i << endl;
        solve();
    }
}