#include <bits/stdc++.h>
using namespace std;
const long long M = 998244353;
const long long g = 3;
long long Pow(long long a, long long n) {
  long long ret = 1;
  while (n) {
    if (n & 1) ret = ret * a % M;
    n >>= 1;
    a = a * a % M;
  }
  return ret;
}
void rader(long long y[], int len) {
  for (int i = 1, j = len / 2; i < len - 1; i++) {
    if (i < j) swap(y[i], y[j]);
    int k = len / 2;
    while (j >= k) {
      j -= k;
      k /= 2;
    }
    if (j < k) j += k;
  }
}
void ntt(long long y[], int len, int on) {
  rader(y, len);
  for (int h = 2; h <= len; h <<= 1) {
    long long wn = Pow(g, (M - 1) / h);
    if (on == -1) wn = Pow(wn, M - 2);
    for (int j = 0; j < len; j += h) {
      long long w = 1;
      for (int k = j; k < j + h / 2; k++) {
        long long u = y[k];
        long long t = w * y[k + h / 2] % M;
        y[k] = (u + t) % M;
        y[k + h / 2] = (u - t + M) % M;
        w = w * wn % M;
      }
    }
  }
  if (on == -1) {
    long long t = Pow(len, M - 2);
    for (int i = 0; i < len; i++) y[i] = y[i] * t % M;
  }
}
long long a[(1 << 20)], b[(1 << 20)];
int n, len;
char s[(1 << 20)];
int T;
bool ans[(1 << 20)];
vector<int> w;
void init() {
  w.clear();
  for (int i = 0; i <= len; i++) {
    a[i] = b[i] = ans[i] = 0;
  }
}
int main() {
  cin >> T;
  while (T--) {
    scanf("%d%s", &n, s);
    if (n == 1)
      printf("1\n1");
    else {
      len = 1;
      while (len <= n * 2) len <<= 1;
      init();
      for (int i = 0; i < n; i++) {
        if (s[i] == 'V')
          a[i] = 1;
        else if (s[i] == 'K')
          b[n - i] = 1;
      }
      ntt(a, len, 1);
      ntt(b, len, 1);
      for (int i = 0; i <= len; i++) a[i] = (a[i] * b[i]) % M;
      ntt(a, len, -1);
      for (int i = 1; i <= n; i++)
        if (a[n - i] == 0 && a[n + i] == 0) ans[i] = true;
      for (int i = 1; i <= n; i++) {
        for (int j = i << 1; j <= n; j += i) ans[i] &= ans[j];
        if (ans[i]) w.push_back(i);
      }
      cout << w.size() << endl;
      for (int i = 0; i < (int)w.size(); i++) printf("%d ", w[i]);
    }
    putchar('\n');
  }
  return 0;
}
