#include <bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<(b);++i)
#define erep(i,a,b) for(int i=a;i<=(int)(b);++i)
#define per(i,a,b) for(int i=(b);i>(a);--i)
#define eper(i,a,b) for(int i=((int)(a));i>=b;--i)
#define pb push_back
#define mp make_pair
#define INF 1e18
#define MOD 1000000007
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
int dy[]={0, 0, 1, -1};
int dx[]={1, -1, 0, 0};
int gcd(int a,int b){return b?gcd(b,a%b):a;}
int lcm(int a,int b){return a/gcd(a, b)*b;}

string s[51];
int h, w, p[52][52];
double ans = DBL_MAX;
int main() {
 ios::sync_with_stdio ( false );
 cin.tie ( 0 );
    cin >> h >> w;
    erep(i, 1, h) cin >> s[i];
    erep(i, 1, h) rep(j, 0, w) {
        int c = s[i][j] - '0';
        p[i][j+1] = c;
    }
    erep(i, 0, h+1) {
        erep(j, 0, w+1) {
            if (i * j == 0 || i == h+1 || j == w+1) 
                p[i][j] = -1;
        }
    }
    erep(i, 0, h+1) {
        erep(j, 0, w+1) {
            if (p[i][j] != -1) continue;
            else {
                double sum = 0.0;
                erep(k, 1, h) {
                    erep(l, 1, w) {
                        if (p[k][l] == 1) {
                            sum += sqrt((i-k)*(i-k) + (j-l)*(j-l));
                        }
                    }
                }
                ans = min(ans, sum);
            }
        }
    }
    printf("%.12f\n", ans);
    return 0;
}