#include <bits/stdc++.h>
using namespace std;
#define mod 1000000007
#define ll long long
#define N 105
#define all(v) v.begin(),v.end()
#define pii pair<int,int>
#define piii pair<int,pii>
#define print(x) cout << #x << "=" << x << "\t";
#define newline cout << endl;

int n;
char s[N][N];
int k;
vector<int> v;
int ff;
int ss;
int dist[N][N];
vector<int> ans;

void shortestPath(int id) {
    queue<int> q;
    bool h[N] = {0};
    q.push(id);
    h[id] = true;
    while (!q.empty()) {
        int top = q.front();
        q.pop();
        for(int i=1;i<=n;i++)
            if (s[top][i] == '1' && !h[i]) {
                dist[id][i] = dist[id][top] + 1;
                q.push(i);
                h[i] = true;
            }
    }
}

int main() {
    //ios::sync_with_stdio(false); cin.tie(NULL);
    scanf("%d", &n);
    for(int i=1;i<=n;i++)
        scanf("%s", s[i] + 1);
    scanf("%d", &k);
    v.resize(k);
    for(int i=0;i<k;i++)
        scanf("%d", &v[i]);
    ff = 0;
    ss = *v.rbegin();

    for(int i=1;i<=n;i++)
        shortestPath(i);

    ans.push_back(v[0]);
    for(int i=1;i<k;i++) {
        if (dist[v[ff]][v[i]] < i - ff) {
            ans.push_back(v[i - 1]);
            ff = i - 1;
            i--;
        }
    }
    ans.push_back(v[k - 1]);

    printf("%d\n", (int)ans.size());
    for(auto u : ans)
        printf("%d ", u);
    return 0;
}