from collections import Counter, deque
from copy import copy
N,Q = map(int,input().split())
S = list(str(input()))
alp = list('abcdefghijklmnopqrstuvwxyz')
s = Counter(sorted(S))
C = deque([copy(s)])

for i in range(N-1,-1,-1):
    s[S[i]] -= 1
    C.appendleft(copy(s))

for _ in range(Q):
    l,r,x = map(int,input().split())
    a,b = C[l-1],C[r]
    count = 0
    for p in alp:
        count += b[p]-a[p]
        if count >= x:
            print(p)
            break