#include <bits/stdc++.h>
using namespace std;
const int nmax = (1 << 20) + 5;
const double pi = acos(-1.0);
complex<double> p1[nmax], p2[nmax], p3[nmax];
string s;
int a[nmax], b[nmax], ok[nmax], c[nmax];
int o[nmax];
int i, lim, lg, j, t, n;
void fft(complex<double> v[], double rev) {
  double L;
  complex<double> U, V, root, put;
  for (i = 0; i < lim; i++)
    if (i < o[i]) swap(v[i], v[o[i]]);
  for (int l = 1; l < lim; l *= 2) {
    L = 2 * l;
    root = {cos(2 * pi / L), sin(2 * pi / L) * rev};
    for (i = 0; i < lim; i += 2 * l) {
      put = {1, 0};
      for (j = 0; j < l; j++) {
        U = v[i + j];
        V = v[i + j + l];
        v[i + j] = U + V * put;
        v[i + j + l] = U - V * put;
        put *= root;
      }
    }
  }
  if (rev == -1) {
    L = lim;
    for (i = 0; i < lim; i++) v[i] /= L;
  }
}
void mult(int A[], int B[], int C[]) {
  for (i = 0; i < lim; i++) {
    o[i] = 0;
    for (j = 0; j < lg; j++)
      if (((1 << j) & i)) o[i] |= (1 << (lg - j - 1));
  }
  for (i = 0; i < lim; i++)
    p1[i] = {(double)A[i], 0}, p2[i] = {(double)B[i], 0};
  fft(p1, 1);
  fft(p2, 1);
  for (i = 0; i < lim; i++) p3[i] = p1[i] * p2[i];
  fft(p3, -1);
  for (i = 0; i < lim; i++) {
    C[i] = (int)round(p3[i].real());
    p1[i] = p2[i] = p3[i] = {0, 0};
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin >> t;
  for (int cnt = 1; cnt <= t; cnt++) {
    cin >> n;
    cin >> s;
    s = " " + s;
    for (i = 1; i <= n; i++) {
      if (s[i] == 'V') a[i] = 1;
      if (s[i] == 'K') b[n - i] = 1;
    }
    lg = 0;
    lim = 1;
    while (lim <= 2 * n) lim *= 2, lg++;
    mult(a, b, c);
    for (i = 1; i <= n; i++) ok[i] = 1;
    for (i = 0; i < lim; i++) {
      if (c[i]) ok[max(i - n, n - i)] = 0;
      a[i] = b[i] = c[i] = 0;
    }
    for (i = 1; i <= n; i++)
      for (j = 2 * i; j <= n; j += i) ok[i] &= ok[j];
    int bune = 0;
    for (i = 1; i <= n; i++)
      if (ok[i]) bune++;
    cout << bune << '\n';
    for (i = 1; i <= n; i++)
      if (ok[i]) cout << i << ' ';
    cout << '\n';
  }
  return 0;
}
