segi

//Siddharth Jha

#include<bits/stdc++.h>
//#include<ext/pb_ds/assoc_container.hpp>
//#include<ext/pb_ds/tree_policy.hpp>
//#include <ext/pb_ds/trie_policy.hpp>
//using namespace __gnu_pbds;
using namespace std;
//typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> pbds;
//typedef trie<string,null_type,trie_string_access_traits<>,pat_trie_tag,trie_prefix_search_node_update> pbtrie;

#define ll                       long long int
#define mod                      1000000007
#define inf                      1e18
#define pb                       push_back
#define vi                       vector<ll>
#define vs                       vector<string>
#define pii                      pair<ll,ll>
#define ump                      unordered_map
#define mp                       make_pair
#define pq_max                   priority_queue<ll>
#define pq_min                   priority_queue<ll,vi,greater<ll> >
#define all(n)                   n.begin(),n.end()
#define ff                       first
#define ss                       second
#define mid(l,r)                 (l+(r-l)/2)
#define bitc(n)                  __builtin_popcount(n)
#define SET(a)                   memset( a, -1, sizeof a )
#define CLR(a)                   memset( a,  0, sizeof a )
#define Pi                       3.141592653589793
#define loop(x,start,end)        for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define _fast                    ios_base::sync_with_stdio(0);  cin.tie(0); cout.tie(0);
#define iter(container,it)       for(__typeof(container.begin()) it = container.begin(); it != container.end(); it++)
#define log(args...)             {string _s = #args; replace(_s.begin(), _s.end(), ',', ' '); stringstream _ss(_s); istream_iterator<string> _it(_ss); err(_it, args); }
#define logarr(arr,a,b)          for(int z=(a);z<=(b);z++) cout<<(arr[z])<<" ";cout<<endl;
template <typename T> T          gcd(T a, T b){if(a%b) return gcd(b,a%b);return b;}
template <typename T> T          lcm(T a, T b){return (a*(b/gcd(a,b)));}
vs tokenizer(string str,char ch) {std::istringstream var((str)); vs v; string t; while(getline((var), t, (ch))) {v.pb(t);} return v;}

void err(istream_iterator<string> it) {}
template<typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args) {
cout << *it << " = " << a << endl;
err(++it, args...);
}
class segtree
{
private:
    int n;
    vector<int> segtree;
public:
    void init(int n)
    {
        this->n = n;
        segtree.resize(4 * n + 1);
    }
    int op(int x, int y)
    {
        return (x + y);
    }
    void updateVal(int x, int l, int r, int idx, int val)
    {
        if (l > idx or r < idx)
            return;
        if (l == r)
        {
            segtree[x] += val;
            return;
        }
        int mid = (l + r) / 2LL;
        updateVal(2 * x, l, mid, idx, val);
        updateVal(2 * x + 1, mid + 1, r, idx, val);
        segtree[x] = op(segtree[2 * x], segtree[2 * x + 1]);
    }
    void set(int idx, int val)
    {
        updateVal(1, 1, n, idx, val);
    }
    int cal(int x, int l, int r, int L, int R)
    {
        if (L <= l and R >= r)
            return segtree[x];
        if (L > r or R < l)
            return 0;
        int mid = (l + r) / 2LL;
        return op(cal(2 * x, l, mid, L, R), cal(2 * x + 1, mid + 1, r, L, R));
    }
    int sum(int l, int r)
    {
        return l > r ? 0 : cal(1, 1, n, l, r);
    }
};

void solve() {

   int n,q;
   cin >> n >> q;
   string s ;
   cin >> s;
   vector<int> arr (n);
   loop (i,0,n) cin >> arr[i];
   vector<vector<int>> ranges (q, vector<int>(2));
   loop (i,0,q) cin >> ranges[i][0] >> ranges[i][1];

   set<pair<int,int>> range;
   for (int i = 0; i < q; i++) {
    range.insert({ranges[i][0],ranges[i][1]});
   }

   segtree seg[26];
   vector<vector<int>> freq (26, vector<int>(n,0));

   for (int i = 0; i < n; i++) {
    int idx = (s[i] - 'a');
    freq[idx][i]++;
   }
   for (int i = 0; i < 26; i++) {
    seg[i].init(n);
    for (int j = 0; j < n; j++){
        seg[i].set(j+1,freq[i][j]);
    }

   }
    bool flag = 1;
    for (int c = 0; c < 26; c++) {
         for (auto r : range) {
            if (seg[c].sum(r.first, r.second) > 1) {
                flag = 0;
                break;
            }
        }
        if (!flag) break;
    }
    if (flag) {
        cout << 0;
        return;
    }
   for (int i=0; i<n; i++) {

        int idx = (s[arr[i]] - 'a'), v = -1, id = arr[i];
        seg[idx].set(id,v);
        flag = 1;
        for (int c = 0; c < 26; c++) {
             for (auto r : range) {
                if (seg[c].sum(r.first, r.second) > 1) {
                    flag = 0;
                    break;
                }
             }
             if (!flag) break;
        }
        if (flag) {
            cout << i+1;
            return;
        }
   }
}

int main(int argc, char const *argv[]){
    _fast
  //#ifndef ONLINE_JUDGE
        //freopen("input.txt", "r", stdin);
        //freopen("output.txt", "w", stdout);
  //#endif
    ll t; cin>>t;
    while(t--){
     solve();
    }
  return 0;
}