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#include <bits/stdc++.h>
#define REP(a,b) for(int a=0; a<(b); ++a)
#define FWD(a,b,c) for(int a=(b); a<(c); ++a)
#define FWDS(a,b,c,d) for(int a=(b); a<(c); a+=d)
#define BCK(a,b,c) for(int a=(b); a>(c); --a)
#define ALL(a) (a).begin(), (a).end()
#define SIZE(a) ((int)(a).size())
#define SQ(a) ((a)*(a))
#define VAR(x) #x ": " << x << " "
#define popcount __builtin_popcount
#define popcountll __builtin_popcountll
#define gcd __gcd
#define x first
#define y second
#define st first
#define nd second
#define pb push_back

using namespace std;

template<typename T> ostream& operator<<(ostream &out, const vector<T> &v){ out << "{"; for(const T &a : v) out << a << ", "; out << "}"; return out; }
template<typename S, typename T> ostream& operator<<(ostream &out, const pair<S,T> &p){ out << "(" << p.st << ", " << p.nd << ")"; return out; }

typedef long long int64;
typedef unsigned long long uint64;
typedef pair<int, int> PII;
typedef pair<int64, int64> PLL;
typedef long double K;
typedef vector<int> VI;

const int dx[] = {0,0,-1,1}; //1,1,-1,1};
const int dy[] = {-1,1,0,0}; //1,-1,1,-1};

const int INF = 1000 * 1000 * 1000;

const int T = 30;

int n, b, r;
bitset<200> unsafe;
bitset<200> out[210];
bitset<200> sum[16][65600];
bitset<200> f16;
bitset<200> u, v;
char buff[210];

unordered_set<bitset<200>> visited;

int main(){
	scanf("%d %d %d", &n, &b, &r);
	FWD(i,0,n){
		scanf("%s", buff);
		FWD(j,0,n) if(buff[j] == '1') out[i].set(j);
	}

	FWD(k,0,16)
		FWD(m,0,1<<16)
			FWD(i,0,16)
				if(m&(1<<i))
					sum[k][m] |= out[k*16+i];

	FWD(i,0,16) f16.set(i);

	FWD(i,b,n) unsafe.set(i);

	FWD(i,0,r){
		int a;
		scanf("%d", &a);
		u.set(a-1);
	}

	int res = 0;
	while(visited.insert(u).nd){
		if((u&unsafe).none()){
			printf("%d\n", res);
			return 0;
		}
		++res;
		v.reset();
		FWD(k,0,16){
			v |= sum[k][(int)(u&f16).to_ulong()];
			u >>= 16;
		}
		u = v;
	}
	printf("-1\n");
	return 0;
}