#include <bits/stdc++.h>
using namespace std;
#define ll long long

const ll N=1e7+100;

ll n,k;
ll b[100],s[100][100];
ll head[N],nxt[N],to[N],fy[N],cnt;
ll dis[N];
bool check[N];
queue<ll> q;

void add(ll u,ll v,ll w){
	to[++cnt]=v;
	fy[cnt]=w;
	nxt[cnt]=head[u];
	head[u]=cnt;
}

void spfa(){
	memset(dis,0x3f,sizeof(dis));
	dis[1]=0;check[1]=1;
	q.push(1);
	while(!q.empty()){
		ll u=q.front();q.pop();
		check[u]=0;
		for (int i=head[u];i;i=nxt[i]){
			ll v=to[i],w=fy[i];
			if (dis[v]>dis[u]+w){
				dis[v]=dis[u]+w;
				if (!check[v]){
					check[v]=1;
					q.push(v);
				}
			}
		}
	}
}

int main(){
	freopen("telephone.in","r",stdin);
	freopen("telephone.out","w",stdout);
	scanf("%lld %lld",&n,&k);
	for (int i=1;i<=n;i++){
		scanf("%lld",&b[i]);
	}
	getchar();
	for (int i=1;i<=k;i++){
		for (int j=1;j<=k;j++){
			char ss=getchar();
			s[i][j]=ss-'0';
		}
		getchar();
	}
	for (int i=1;i<=n;i++){
		for (int j=1;j<=n;j++){
			if (s[b[i]][b[j]]==1&&i!=j){
				add(i,j,abs(i-j));
			}
		}
	}
	spfa();
	if (dis[n]==0x3f3f3f3f3f3f3f3f) printf("-1");
	else printf("%lld",dis[n]);
	return 0;
}