dsu on tree

/*dsu on tree */

int n,big[MAX];vi v[MAX];char c[MAX];

int ans[MAX];int vis[MAX];vector<pii>ques[MAX];

int Sz[MAX],col[MAX][30];int cnt,maxi;vi v2;char str[MAX];



void dfs2(int s,int p){
    Sz[s] = 1;
    for(auto it : v[s]){
        if(it==p)continue;
        dfs2(it,s);
        Sz[s]+=Sz[it];
    }
}

void add(int s,int p,int val,int depth){
    col[depth][c[s]-96]+=val;
    for(auto it : v[s]){
        if(p==it||big[it])continue;
        add(it,s,val,depth+1);
    }
}


void dfs(int s,int p,int keep,int depth){
    int b = -1,mx = -1;
    for(auto it : v[s]){
        if(Sz[it]>mx&&it!=p){
            mx = Sz[it];
            b = it;
        }
    }

    for(auto it : v[s]){
        if(it!=b&&it!=p)dfs(it,s,0,depth+1);
    }
    if(b!=-1)dfs(b,s,1,depth+1),big[b] = 1;
    add(s,p,1,depth);
    for(auto it : ques[s]){
        int jor = 0,bijor = 0;
        for(char ch = 'a';ch<='z';ch++){
            if(col[it.ff][ch-96]&1)bijor++;
            else jor++;
        }
        if(bijor<=1)ans[it.ss] = 1;
        else ans[it.ss] = 0;
    }
    //cout<<s<<" balsal "<<maxi<<endl;
    if(b!=-1)big[b] = 0;
    if(!keep)add(s,p,-1,depth),cnt=0,maxi=0;




}


int main()
{
   // booster()
    ///read("input.txt");
    scani(n);
    int q;
    scani(q);
    string st;
    for(int i = 0;i<n-1;i++){
        int a;
        scani(a);
        v[a].pb(i+2);
    }
    scanf(" %s",str);
    st = str;
    for(int i = 0;i<n;i++)c[i+1] = st[i];
    for(int i = 0;i<q;i++){
        int a,b;
        scani2(a,b);
        ques[a].pb(pii(b,i+1));
    }
    dfs2(1,0);
    dfs(1,0,1,1);
    for(int i = 1;i<=q;i++){
        if(ans[i])puts("Yes");
        else puts("No");
    }


    return 0;
}