#include<bits/stdc++.h>
#define FIN freopen("./D.in","r",stdin)
#define debug(x) cout<<#x"=["<<x<<"]"<<endl
using namespace std;
typedef long long ll;
const int maxn(1e2+5);
const double pi=acos(-1);
ll n,k,w[maxn];
string e[maxn];
struct clique{//存储一个团
    ll w;//当前团的权值
    int num;//当前团内点数
    vector<int> p;//当前团内各点
    bool operator < (const clique &c) const {
        return w>c.w;
    }
}cli[maxn],qt;
priority_queue<clique> q;
int main(){
#ifndef ONLINE_JUDGE
    FIN;
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin>>n>>k;
    for(int i=1;i<=n;i++){
        cin>>w[i];
        cli[i].w=w[i];
        cli[i].num=0;
        cli[i].p.push_back(i);
        q.push(cli[i]);
    }
    for(int i=1;i<=n;i++){
        cin>>e[i];
    }
    k--;
    if(k==0){
        cout<<0<<endl;
        return 0;
    }
    while(!q.empty()){
        qt=q.top();
        q.pop();
        k--;
        if(k==0){
            cout<<qt.w<<endl;
            return 0;
        }
        int now=qt.p[qt.num];
        bool flag;
        for(int i=now+1;i<=n;i++){
            flag=1;
            for(int j=0;j<=qt.num;j++){
                if(e[qt.p[j]][i-1]=='0'){
                    flag=0;
                    break;
                }
            }
            if(flag){
                qt.num++;
                qt.p.push_back(i);
                qt.w+=w[i];
                q.push(qt);
                qt.num--;
                qt.p.pop_back();
                qt.w-=w[i];
            }
        }
    }
    cout<<-1<<endl;
}

#include<bits/stdc++.h>
#define FIN freopen("./F.in","r",stdin)
#define debug(x) cout<<#x"=["<<x<<"]"<<endl
using namespace std;
typedef long long ll;
const ll maxn(1e2+5);
const double pi=acos(-1);
ll n,v[maxn][maxn],ans,num1,num2,s1[maxn],s2[maxn];
void dfs(ll index,ll sum){
    if(num1==n&&num2==n){
        ans=max(sum,ans);
    }
    if(num1<n){
        ll k=0;
        s1[++num1]=index;
        for(ll i=1;i<=num2;i++){
            k+=v[s1[num1]][s2[i]];
        }
        dfs(index+1,sum+k);
        num1--;
    }
    if(num2<n){
        ll k=0;
        s2[++num2]=index;
        for(ll i=1;i<=num1;i++){
            k+=v[s2[num2]][s1[i]];
        }
        dfs(index+1,sum+k);
        num2--;
    }
}
int main(){
#ifndef ONLINE_JUDGE
    FIN;
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin>>n;
    for(ll i=1;i<=n*2;i++){
        for(ll j=1;j<=n*2;j++){
            cin>>v[i][j];
        }
    }
    dfs(1,0);
    cout<<ans<<endl;
}

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF(0x3f3f3f3f3f3f3f);
const double ESP(1e-9);
const ll mod(1e9+7);
#define per(i, a, b) for(int i=a; i<b; i++)
#define rep(i, a, b) for(int i=b-1; i>=a; i--)
#define mem(a, b) memset(a, b, sizeof(a))
ll powmod(ll a, ll b) { ll res = 1; a %= mod; assert(b >= 0); for (; b; b >>= 1) { if (b & 1)res = res * a%mod; a = a * a%mod; }return res; }
ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
 
const int MAXN(1e3 + 7);
int n, m;
string str;
int high[MAXN];
 
int mxx, mxx2;
int stkhg[MAXN], stkpos[MAXN];
int cnt;
 
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
 
    cin >> n >> m;
    high[m+1] = 0;
    per(i, 1, n+1) {
        cin >> str;
        per(j, 1, m+1) {
            high[j] = str[j-1]=='0'?0:high[j]+1;
        }
        stkhg[0] = stkpos[0] = cnt = 0;
        per(j, 1, m+2) {
            if(high[j]>stkhg[cnt]) {
                stkhg[++cnt] = high[j];
                stkpos[cnt] = j;
            } else if(high[j]<stkhg[cnt]) {
                while (high[j] < stkhg[cnt]) {
                    int area = (j - stkpos[cnt]) * stkhg[cnt];
                    if (area >= mxx) {
                        mxx2 = mxx;
                        mxx = area;
                        mxx2 = max(mxx2, max(area - stkhg[cnt], area - (j - stkpos[j])));
                    } else if (area > mxx2) {
                        mxx2 = area;
                    }
                    cnt--;
                }
                if(stkhg[cnt]!=high[j]) {
                    stkhg[++cnt] = high[j];
                }
            }
        }
    }
 
    cout << mxx2 << endl;
 
    return 0;
}