#include <bits/stdc++.h>
#define REP(i, a, n) for(ll i = ((ll) a); i < ((ll) n); i++)
using namespace std;
typedef long long ll;

int main(void) {
  ll H, W;
  cin >> H >> W;
  vector<vector<ll>> P(H + 1, vector<ll>(W + 1));
  REP(i, 1, H + 1) {
    string s; cin >> s;
    REP(j, 1, W + 1) {
      P[i][j] = s[j - 1] - '0';
    }
  }

  double ans = 1e20;
  REP(i, 0, H + 2) REP(j, 0, W + 2) {
    ll cnt = 0;
    if(i == 0) cnt++;
    if(i == H + 1) cnt++;
    if(j == 0) cnt++;
    if(j == W + 1) cnt++;
    if(cnt != 1) continue;
    double t = 0;
    REP(y, 1, H + 1) REP(x, 1, W + 1) {
      if(P[y][x] == 1) {
        t += sqrt((i - y) * (i - y) + (j - x) * (j - x));
      }
    }
    ans = min(ans, t);
  }
  printf("%.15lf\n", ans);
}