#include <cstdio>
#include <cstring>
#include <queue>
#include <vector>

void ParseIn();
void Core();
void WriteOut();

int main() {
  freopen("telephone.in", "r", stdin);
  freopen("telephone.out", "w", stdout);
  ParseIn();
  Core();
  WriteOut();
  return 0;
}

template <typename T> T read();
template <typename T> void write(T, char);
template <typename T> T abs(T);
char readc();

const int MAXN = 5e4 + 10;
const int MAXK = 60;

int n, k;
int a[MAXN];
::std::vector<int> g[MAXK];
::std::vector<int> colors[MAXK];

void ParseIn() {
  n = read<int>(), k = read<int>();
  for (int i = 1; i <= n; ++i) {
    a[i] = read<int>();
    colors[a[i]].push_back(i);
  }
  for (int i = 1; i <= k; ++i) {
    for (int j = 1; j <= k; ++j) {
      if (readc() == '1') g[i].push_back(j);
    }
  }
}

::std::priority_queue<::std::pair<int, int>> pq;
int dis[MAXN];
bool vis[MAXN];
void Core() {
  memset(dis, 0x3f, sizeof dis);
  dis[1] = 0;
  pq.push(::std::make_pair(0, 1));
  while (!pq.empty()) {
    int u = pq.top().second;
    pq.pop();
    if (vis[u]) continue;
    vis[u] = true;
    for (auto c : g[a[u]]) {
      for (auto v : colors[c]) {
        int w = abs(v - u);
        if (dis[u] + w < dis[v]) {
          dis[v] = dis[u] + w;
          pq.push(::std::make_pair(-dis[v], v));
        }
      }
    }
  }
}

void WriteOut() {
  write(dis[n] == 0x3f3f3f3f ? -1 : dis[n], '\n');
}

template <typename T> T abs(T x) {
  return x < 0 ? -x : x;
}

#define isspace(ch) (ch == ' ' || ch == '\n')
char readc() {
  char ch = getchar();
  for (; isspace(ch); ch = getchar());
  return ch;
}
#undef isspace

#define isdigit(ch) (ch >= '0' && ch <= '9')
template <typename T> T read() {
  T res = 0, f = 1;
  char ch = getchar();
  for (; !isdigit(ch); ch = getchar())
    if (ch == '-') f = -1;
  for (; isdigit(ch); ch = getchar()) res = (res << 3) + (res << 1) + (ch ^ 48);
  return res * f;
}
#undef isdigit

template <typename T> void write(T x, char ed) {
  if (x < 0) x = -x, putchar('-');
  int sta[sizeof(T) << 2], top = 0;
  do {
    sta[++top] = x % 10;
    x /= 10;
  } while (x);
  while (top) {
    putchar(sta[top--] ^ 48);
  }
  putchar(ed);
}