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

alpha =['a','b','c','d','e','f','g','h','i','j','k','l','m','n',
        'o','p','q','r','s','t','u','v','w','x','y','z']

data = [[[0] for k in range(26)] for _ in range(N)]

for i in range(N):
    for k in range(26):
        data[i][k] = S.count(alpha[k], 0, i+1)

a = [0]*26

for i in range(Q):
    l, r, x = list(map(int, input().split()))
    if l > 1:
        DATA = data[l-2]
    else:
        DATA = a

    d = data[r-1][0] - DATA[0]
    for j in range(26):
        if d >= x:
            print(alpha[j])
            break
        d += data[r-1][j+1] - DATA[j+1]