#include<bits/stdc++.h>
using namespace std;
#define rep(i,j,k) for(int i = j;i <= k;++i)
#define repp(i,j,k) for(int i = j;i >= k;--i)
#define ll long long
#define pb push_back
#define rank Rank
#define mp make_pair
#define P pair<int,int>
#define fr first
#define se second   
#define rept(i,x) for(int i = linkk[x];i;i = e[i].n)
int rd() {
    int sum = 0;char c = getchar();bool flag = true;
    while(c < '0' || c > '9') {if(c == '-') flag = false;c = getchar();}
    while(c >= '0' && c <= '9') sum = sum * 10 + c - 48,c = getchar();
    if(flag) return sum;
    else return -sum;
}
int T;
vector<int>G[201000],node[201000];
int fa[201000],dep[201000],rank[201000];
int n,m,mx_dep;
char ans[201000];
bool spe[201000];
// 0 ~ n
void dfs(int x) {
    mx_dep = max( mx_dep , dep[x] );
    node[dep[x]].pb(x);  
    for(auto y:G[x])
        dep[y] = dep[x] + 1 , dfs(y);
}
int get(int x,int y) {
    if( spe[x] && !spe[y] ) return 1;
    if( !spe[x] && spe[y] ) return 0;
    for(int i = 0;i < (int)(G[x].size()) && i < (int)(G[y].size());++i) {
     /*   if( min(x,y) == 7 && max(x,y) == 8 ) {
           printf("#%d %d\n",G[x][i],G[y][i]);
        }*/
        if( rank[G[x][i]] != rank[G[y][i]] ) 
            return rank[G[x][i]] < rank[G[y][i]];
    }
    if( (int)(G[x].size()) != (int)(G[y].size()) )
        return (int)(G[x].size()) > (int)(G[y].size());
    else 
        return 2;
}
bool cmp( int x,int y ) {
    int res = get(x,y);
    if( res != 2 ) return res;
    else return x < y;
}
void dfs1(int x) {
    char ch = 'a';
   // printf("#%d\n",x);
 //   for(auto y:G[x]) printf("#%d ",y); printf("\n\n");
    for(int i = 0;i < (int)(G[x].size());++i) {
        int y = G[x][i];
        dfs1(y);
    }
    sort(G[x].begin(),G[x].end(),cmp);
    for(int i = 0;i < (int)(G[x].size());++i) {
        int y = G[x][i];
        ans[y] = ch;
        ch++;
    }
}
int TTT;
void work() {
    n = rd(); m = rd();
// if(TTT == 40 && T == 50000) cerr<<n<<" "<<m<<endl;
    rep(x,0,n) {
        spe[x] = false; G[x].clear();
        node[x].clear(); rank[x] = 0;
        ans[x] = 'a'; fa[x] = 0;
    }

    rep(i,1,n) {int x = rd(); fa[i] = x; G[fa[i]].pb(i);}

// if(TTT==40 && T == 50000) rep(i,1,n)  printf("%d ",fa[i]);
// if(TTT==40 && T == 50000) printf("\n");

    rep(i,1,m) {
        int x = rd(); 
  //  if(TTT == 40 && T == 50000) printf("%d ",x);  
        spe[x] = true;
    } 
//if(TTT==40 && T == 50000) printf("\n");
    dfs(0);
    repp(i,mx_dep,0) {

        for(auto x:node[i])
            sort(G[x].begin(),G[x].end(),cmp);
        sort( node[i].begin() , node[i].end() , cmp );
        int rk = 1;
        rank[node[i][0]] = rk;
        for(int j = 1;j < (int)(node[i].size());++j)
            if( get(node[i][j],node[i][j-1]) != 2 ) rank[node[i][j]] = ++rk;
            else rank[node[i][j]] = rk;
        
        // for(auto x:node[i]) printf("*%d ",x); printf("\n");
        // for(auto x:node[i]) printf("*%d ",rank[x]); printf("\n\n");
    }
    dfs1(0);
    //if(TTT == 40 || T != 50000) {
    rep(i,1,n) putchar(ans[i]);
    printf("\n");
    //}
}
int main(){
    // freopen("input.txt","r",stdin);
    T = rd();
    for(TTT=1;TTT<=T;++TTT) {
        work();
    }
	return 0;
}