#include <bits/stdc++.h>
namespace atcoder {
namespace internal {
std::vector<int> sa_naive(const std::vector<int>& s) {
  int n = int(s.size());
  std::vector<int> sa(n);
  std::iota(sa.begin(), sa.end(), 0);
  std::sort(sa.begin(), sa.end(), [&](int l, int r) {
    if (l == r) return false;
    while (l < n && r < n) {
      if (s[l] != s[r]) return s[l] < s[r];
      l++;
      r++;
    }
    return l == n;
  });
  return sa;
}
std::vector<int> sa_doubling(const std::vector<int>& s) {
  int n = int(s.size());
  std::vector<int> sa(n), rnk = s, tmp(n);
  std::iota(sa.begin(), sa.end(), 0);
  for (int k = 1; k < n; k *= 2) {
    auto cmp = [&](int x, int y) {
      if (rnk[x] != rnk[y]) return rnk[x] < rnk[y];
      int rx = x + k < n ? rnk[x + k] : -1;
      int ry = y + k < n ? rnk[y + k] : -1;
      return rx < ry;
    };
    std::sort(sa.begin(), sa.end(), cmp);
    tmp[sa[0]] = 0;
    for (int i = 1; i < n; i++) {
      tmp[sa[i]] = tmp[sa[i - 1]] + (cmp(sa[i - 1], sa[i]) ? 1 : 0);
    }
    std::swap(tmp, rnk);
  }
  return sa;
}
template <int THRESHOLD_NAIVE = 10, int THRESHOLD_DOUBLING = 40>
std::vector<int> sa_is(const std::vector<int>& s, int upper) {
  int n = int(s.size());
  if (n == 0) return {};
  if (n == 1) return {0};
  if (n == 2) {
    if (s[0] < s[1]) {
      return {0, 1};
    } else {
      return {1, 0};
    }
  }
  if (n < THRESHOLD_NAIVE) {
    return sa_naive(s);
  }
  if (n < THRESHOLD_DOUBLING) {
    return sa_doubling(s);
  }
  std::vector<int> sa(n);
  std::vector<bool> ls(n);
  for (int i = n - 2; i >= 0; i--) {
    ls[i] = (s[i] == s[i + 1]) ? ls[i + 1] : (s[i] < s[i + 1]);
  }
  std::vector<int> sum_l(upper + 1), sum_s(upper + 1);
  for (int i = 0; i < n; i++) {
    if (!ls[i]) {
      sum_s[s[i]]++;
    } else {
      sum_l[s[i] + 1]++;
    }
  }
  for (int i = 0; i <= upper; i++) {
    sum_s[i] += sum_l[i];
    if (i < upper) sum_l[i + 1] += sum_s[i];
  }
  auto induce = [&](const std::vector<int>& lms) {
    std::fill(sa.begin(), sa.end(), -1);
    std::vector<int> buf(upper + 1);
    std::copy(sum_s.begin(), sum_s.end(), buf.begin());
    for (auto d : lms) {
      if (d == n) continue;
      sa[buf[s[d]]++] = d;
    }
    std::copy(sum_l.begin(), sum_l.end(), buf.begin());
    sa[buf[s[n - 1]]++] = n - 1;
    for (int i = 0; i < n; i++) {
      int v = sa[i];
      if (v >= 1 && !ls[v - 1]) {
        sa[buf[s[v - 1]]++] = v - 1;
      }
    }
    std::copy(sum_l.begin(), sum_l.end(), buf.begin());
    for (int i = n - 1; i >= 0; i--) {
      int v = sa[i];
      if (v >= 1 && ls[v - 1]) {
        sa[--buf[s[v - 1] + 1]] = v - 1;
      }
    }
  };
  std::vector<int> lms_map(n + 1, -1);
  int m = 0;
  for (int i = 1; i < n; i++) {
    if (!ls[i - 1] && ls[i]) {
      lms_map[i] = m++;
    }
  }
  std::vector<int> lms;
  lms.reserve(m);
  for (int i = 1; i < n; i++) {
    if (!ls[i - 1] && ls[i]) {
      lms.push_back(i);
    }
  }
  induce(lms);
  if (m) {
    std::vector<int> sorted_lms;
    sorted_lms.reserve(m);
    for (int v : sa) {
      if (lms_map[v] != -1) sorted_lms.push_back(v);
    }
    std::vector<int> rec_s(m);
    int rec_upper = 0;
    rec_s[lms_map[sorted_lms[0]]] = 0;
    for (int i = 1; i < m; i++) {
      int l = sorted_lms[i - 1], r = sorted_lms[i];
      int end_l = (lms_map[l] + 1 < m) ? lms[lms_map[l] + 1] : n;
      int end_r = (lms_map[r] + 1 < m) ? lms[lms_map[r] + 1] : n;
      bool same = true;
      if (end_l - l != end_r - r) {
        same = false;
      } else {
        while (l < end_l) {
          if (s[l] != s[r]) {
            break;
          }
          l++;
          r++;
        }
        if (l == n || s[l] != s[r]) same = false;
      }
      if (!same) rec_upper++;
      rec_s[lms_map[sorted_lms[i]]] = rec_upper;
    }
    auto rec_sa = sa_is<THRESHOLD_NAIVE, THRESHOLD_DOUBLING>(rec_s, rec_upper);
    for (int i = 0; i < m; i++) {
      sorted_lms[i] = lms[rec_sa[i]];
    }
    induce(sorted_lms);
  }
  return sa;
}
}  // namespace internal
std::vector<int> suffix_array(const std::vector<int>& s, int upper) {
  assert(0 <= upper);
  for (int d : s) {
    assert(0 <= d && d <= upper);
  }
  auto sa = internal::sa_is(s, upper);
  return sa;
}
template <class T>
std::vector<int> suffix_array(const std::vector<T>& s) {
  int n = int(s.size());
  std::vector<int> idx(n);
  iota(idx.begin(), idx.end(), 0);
  sort(idx.begin(), idx.end(), [&](int l, int r) { return s[l] < s[r]; });
  std::vector<int> s2(n);
  int now = 0;
  for (int i = 0; i < n; i++) {
    if (i && s[idx[i - 1]] != s[idx[i]]) now++;
    s2[idx[i]] = now;
  }
  return internal::sa_is(s2, now);
}
std::vector<int> suffix_array(const std::string& s) {
  int n = int(s.size());
  std::vector<int> s2(n);
  for (int i = 0; i < n; i++) {
    s2[i] = s[i];
  }
  return internal::sa_is(s2, 255);
}
template <class T>
std::vector<int> lcp_array(const std::vector<T>& s,
                           const std::vector<int>& sa) {
  int n = int(s.size());
  assert(n >= 1);
  std::vector<int> rnk(n);
  for (int i = 0; i < n; i++) {
    rnk[sa[i]] = i;
  }
  std::vector<int> lcp(n - 1);
  int h = 0;
  for (int i = 0; i < n; i++) {
    if (h > 0) h--;
    if (rnk[i] == 0) continue;
    int j = sa[rnk[i] - 1];
    for (; j + h < n && i + h < n; h++) {
      if (s[j + h] != s[i + h]) break;
    }
    lcp[rnk[i] - 1] = h;
  }
  return lcp;
}
std::vector<int> lcp_array(const std::string& s, const std::vector<int>& sa) {
  int n = int(s.size());
  std::vector<int> s2(n);
  for (int i = 0; i < n; i++) {
    s2[i] = s[i];
  }
  return lcp_array(s2, sa);
}
template <class T>
std::vector<int> z_algorithm(const std::vector<T>& s) {
  int n = int(s.size());
  if (n == 0) return {};
  std::vector<int> z(n);
  z[0] = 0;
  for (int i = 1, j = 0; i < n; i++) {
    int& k = z[i];
    k = (j + z[j] <= i) ? 0 : std::min(j + z[j] - i, z[i - j]);
    while (i + k < n && s[k] == s[i + k]) k++;
    if (j + z[j] < i + z[i]) j = i;
  }
  z[0] = n;
  return z;
}
std::vector<int> z_algorithm(const std::string& s) {
  int n = int(s.size());
  std::vector<int> s2(n);
  for (int i = 0; i < n; i++) {
    s2[i] = s[i];
  }
  return z_algorithm(s2);
}
}  // namespace atcoder
int hash[5010], DP[5010];
char x[5010];
int check[5010];
std::vector<char> V;
std::vector<int> SA, LCP;
int main() {
  int Case;
  scanf("%d", &Case);
  while (Case--) {
    V.clear();
    int a;
    scanf("%d", &a);
    scanf("%s", x + 1);
    for (int i = 1; i <= a; i++) V.push_back(x[i]);
    SA = atcoder::suffix_array<char>(V);
    LCP = atcoder::lcp_array<char>(V, SA);
    for (int i = 0; i < SA.size(); i++) hash[SA[i] + 1] = i + 1;
    for (int i = a; i >= 1; i--) {
      int S = a - i + 1;
      DP[i] = S;
      check[hash[i]] = a;
      for (int j = hash[i] + 1; j <= a; j++)
        check[j] = check[j - 1] < LCP[j - 2] ? check[j - 1] : LCP[j - 2];
      for (int j = i + 1; j <= a; j++) {
        if (hash[i] < hash[j]) {
          int t = check[hash[j]];
          DP[i] = DP[i] > S + DP[j] - t ? DP[i] : S + DP[j] - t;
        }
      }
    }
    int max = 0;
    for (int i = 1; i <= a; i++) max = max > DP[i] ? max : DP[i];
    printf("%d\n", max);
  }
}
