#include <iostream>
#include <queue>
#include <vector>
using namespace std;


int main() {
    int p, n;
    cin >> p >> n;

    queue<int> q;
    vector<bool> visited(14, false);
    for(int i = 0; i < n; i++) {
        int x;
        cin >> x;
        visited[x] = true;
    }

    vector<bool> vis(100000, false);
    q.push(100);
    q.push(0);
    vis[100] = true;
    for(int i = 0; i < 99999; i++) {
        bool moze = true;
        int x = i;
        int cnt = 0;
        while(x > 0) {
            int digit = x % 10;
            if(visited[digit]) {
                moze = false;
                break;
            }
            cnt++;
            x /= 10;

        }
        if(moze and i != 100) {
            q.push(i);
            q.push(cnt);
            vis[i] = true;
        }
    }

    while(!q.empty()) {
        int number = q.front();
        q.pop();
        int dist = q.front();
        q.pop();

        if(number == p) {
            cout << min(dist, p - 100) << endl;
            return 0;
        }

        if(number + 1 < 100000 and !vis[number + 1]) {
            q.push(number + 1);
            q.push(dist + 1);
            vis[number + 1] = true;
        }
        if(number - 1 >= 0 and !vis[number - 1]) {
            q.push(number - 1);
            q.push(dist + 1);
            vis[number - 1] = true;
        }
    }

    return 0;
}