import sys
from string import ascii_lowercase as ALPHABET

input=sys.stdin.readline

N,Q=map(int,input().split())
S="*"+input()

T={x:[0]*(N+1) for x in ALPHABET}

for x in ALPHABET:
    U=T[x]
    for i in range(1,N+1):
        if S[i]==x:
            U[i]=U[i-1]+1
        else:
            U[i]=U[i-1]

for _ in range(Q):
    L,R,X=map(int,input().split())

    K=0
    for x in ALPHABET:
        K+=T[x][R]-T[x][L-1]
        if K>=X:
            print(x)
            break