#include <cstdio>
#include <vector>
#include <map>
#include <algorithm>

#define X first
#define Y second
#define PB push_back

using namespace std;

typedef pair < int, int > pii;

const int N = 2e5 + 500;
const int INF = 0x3f3f3f3f;

vector < int > v[N], raz[N];
vector < pair < vector < int >, int > > red;
int miin[N], key[N], dep[N], ima[N];
int ord[N], p[N];
char tata[N];

bool cmp(int A, int B){
    if(ord[A] == ord[B]) return A < B;
    return ord[A] < ord[B];
}

void solve(){
    int n, m; scanf("%d%d", &n, &m);
    for(int i = 0;i <= n;i++) v[i].clear(), key[i] = ima[i] = ord[i] = 0;
    for(int i = 1;i <= n;i++) {
        scanf("%d", p + i);
        v[p[i]].PB(i);
        dep[i] = 1 + dep[p[i]];
        raz[dep[i]].PB(i);
    }
    raz[0].PB(0);
    for(;m--;) {int x; scanf("%d", &x); key[x] = 1;}
    for(int i = n;i >= 0;i--) {
        for(int j : v[i]) ima[i] |= ima[j];
        ima[i] |= key[i];
    }
    for(int i = n;i >= 0;i--) {
        if(raz[i].empty()) continue;
        for(int x : raz[i]) {
            sort(v[x].begin(), v[x].end(), cmp);
            for(int i = 0;i < (int)v[x].size();i++)
                tata[v[x][i]] = 'a' + i;
            if(!ima[x]) {
                ord[x] = INF;
                continue;
            }
            vector < int > ja;
            if(key[x]) ja.PB({-1});
            for(int y : v[x]) if(ima[y]) ja.PB(ord[y]);
            ja.PB(INF);
            red.PB({ja, x});
        }
        sort(red.begin(), red.end());
        int aa = 0;
        for(int i = 0;i < (int)red.size();i++) {
            if(i && red[i].X != red[i - 1].X) aa++;
            ord[red[i].Y] = aa;
        }
        red.clear(); raz[i].clear();
    }
    for(int i = 1;i <= n;i++)
        printf("%c", tata[i]);
    printf("\n");
}

int main(){
    int T; scanf("%d", &T);
    for(;T--;) solve();
    return 0;
}