#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cstring>

#define MAXN 10
#define MAXVAL 9

using namespace std;

int n;
int len[MAXN + 1];
int a[MAXN + 1][MAXVAL + 1];
int a_mask[MAXN + 1];

bool transition[MAXN + 1][MAXVAL + 1][MAXN + 1];

int stay_mask[MAXN + 1][MAXVAL + 1];

bool Transition(int x, int xi, int y) {
  if (a_mask[y] & ~a_mask[x]) return false;
  for (int yi = 0; yi < len[y]; ++yi) {
    if (a[y][yi] == a[x][xi]) ++xi;
  }
  return xi == len[x];
}

int StayMask(int x, int xi) {
  int mask = 0;
  for (int i = 0; i < xi; ++i) {
    mask |= 1 << a[x][i];
  }
  return mask;
}

const int oo = MAXN * MAXVAL + 1;
char memo[MAXN + 1][MAXVAL + 1][MAXN + 1][MAXVAL + 1][1 << MAXN];

int Rec(int l, int li, int r, int ri, int used_mask) {
  used_mask &= (1 << n) - 1;
  if (li == 0 && ri == len[r] && used_mask == (1 << n) - 1) return 0;

  if (memo[l][li][r][ri][used_mask] >= 0) return memo[l][li][r][ri][used_mask];

  int ret = oo;
  if (l != n && li == 0) {
    for (int i = 0; i <= n; ++i) {
      if ((used_mask >> i) & 1) continue;
      for (int j = 0; j <= len[i]; ++j) {
        if (!transition[i][j][l]) continue;
        ret = min(ret, Rec(i, j, r, ri, used_mask | (1 << i)));
      }
    }
  } else {
    for (int i = 0; i < n; ++i) {
      if ((used_mask >> i) & 1) continue;
      if (!transition[r][ri][i]) continue;
      ret = min(ret, Rec(l, li, i, 0, used_mask | (1 << i)));
    }
    
    for (int val = 1; val <= MAXVAL; ++val) {
      if (val == a[l][li - 1] && val == a[r][ri]) {
        ret = min(ret, 1 + Rec(l, li - 1, r, ri + 1, used_mask));
      }
      if (val == a[l][li - 1] && ((stay_mask[r][ri] >> val) & 1)) {
        ret = min(ret, 1 + Rec(l, li - 1, r, ri, used_mask));
      }
      if (((stay_mask[l][li] >> val) & 1) && val == a[r][ri]) {
        ret = min(ret, 1 + Rec(l, li, r, ri + 1, used_mask));
      }
    }
  }
  return memo[l][li][r][ri][used_mask] = ret;
}

int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) {
    for (len[i] = 0;; ++len[i]) {
      scanf("%d", &a[i][len[i]]);
      if (a[i][len[i]] == 0) break;
      a_mask[i] |= (1 << a[i][len[i]]);
    }
  }
  len[n] = 0;

  for (int x = 0; x <= n; ++x) {
    for (int xi = 0; xi <= len[x]; ++xi) {
      if (x == n) {
        stay_mask[x][xi] = (1 << (MAXVAL + 1)) - 1;
      } else {
        stay_mask[x][xi] = StayMask(x, xi);
      }
      for (int y = 0; y <= n; ++y) {
        if (x == y) continue;
        if (x == n) transition[x][xi][y] = true;
        else transition[x][xi][y] = Transition(x, xi, y);
      }
    }
  }

  memset(memo, -1, sizeof memo);
  int ret = oo;
  for (int i = 0; i <= n; ++i) {
    int result = Rec(i, len[i], n, 0, (1 << i));
    if (result < ret) ret = result;
  }
  if (ret == oo) printf("-1\n");
  else printf("%d\n", ret);
  return 0;
}