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

alp = [chr(ord("a")+i) for i in range(26)]
rui = {alp[i]: [0]*(N+1) for i in range(26)}

for i in range(N):
    for a in alp:
        if S[i]==a:
            rui[a][i] += 1
        rui[a][i] += rui[a][i-1]

anss = []
for _ in range(Q):
    L, R, X = map(int, input().split())
    c = 0
    for a in alp:
        c += rui[a][R-1]-rui[a][L-2]
        if c >= X:
            anss.append(a)
            break

for ans in anss:
    print(ans)