import sys

input_data = sys.stdin.read().split()
if not input_data:
    sys.exit()

MOD = 998244353
G = 3

def ntt(a, invert):
    n = len(a)
    j = 0
    for i in range(1, n):
        bit = n >> 1
        while j & bit:
            j ^= bit
            bit >>= 1
        j ^= bit
        if i < j:
            a[i], a[j] = a[j], a[i]
    step = 2
    while step <= n:
        half = step >> 1
        wlen = pow(G, (MOD - 1) // step, MOD)
        if invert:
            wlen = pow(wlen, MOD - 2, MOD)
        w = [1] * half
        curr = 1
        for i in range(half):
            w[i] = curr
            curr = (curr * wlen) % MOD
        for i in range(0, n, step):
            for j in range(half):
                u = a[i + j]
                v = (a[i + j + half] * w[j]) % MOD
                a[i + j] = (u + v) % MOD
                a[i + j + half] = (u - v + MOD) % MOD
        step <<= 1
    if invert:
        n_inv = pow(n, MOD - 2, MOD)
        for i in range(n):
            a[i] = (a[i] * n_inv) % MOD

def multiply(a, b):
    if not a or not b:
        return []
    sz = len(a) + len(b) - 1
    n = 1
    while n < sz:
        n <<= 1
    a = a + [0] * (n - len(a))
    b = b + [0] * (n - len(b))
    ntt(a, False)
    ntt(b, False)
    for i in range(n):
        a[i] = (a[i] * b[i]) % MOD
    ntt(a, True)
    return a[:sz]
t = int(input_data[0])
ptr = 1
for _ in range(t):
    if ptr >= len(input_data):
        break
    n = int(input_data[ptr])
    s = input_data[ptr+1]
    ptr += 2
    A = [0] * n
    B = [0] * n
    for i in range(n):
        if s[i] == 'V':
            A[i] = 1
        elif s[i] == 'K':
            B[n - 1 - i] = 1
    C = multiply(A, B)
    bad = [False] * (n + 1)
    for k in range(len(C)):
        if C[k] > 0:
            dist = abs(n - 1 - k)
            if dist <= n:
                bad[dist] = True    
    ans = []
    for p in range(1, n + 1):
        valid = True
        for m in range(p, n + 1, p):
            if bad[m]:
                valid = False
                break
        if valid:
            ans.append(p)            
    print(len(ans))
    print(*(ans))