#include <bits/stdc++.h>
using namespace std;
using ll=long long;
#define rep(i,n) for(int i=0; i<(n); i++)

int N,Q;
string S;
vector<vector<int>> C;

int main(){
  cin>>N>>Q>>S;
  C.assign(27,vector<int>(N+1,0));
  rep(i,N){
    C[S[i]-'a'+1][i+1]++;
  }
  rep(j,27) rep(i,N) C[j][i+1] += C[j][i];
  rep(j,26) rep(i,N+1) C[j+1][i] += C[j][i];
  rep(i,Q){
    int l,r,x; cin>>l>>r>>x; l--;
    for(int j=0; j<26; j++){
      if(C[j+1][r] - C[j+1][l] >= x){
        cout<<(char)('a'+j)<<"\n";
        break;
      }
    }
  }
  return 0;
}