#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <unordered_map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
#include <float.h>
using namespace std;

long long MOD = 1000000007;

int main() {
    int H,W;
    cin >> H >> W;
    vector< vector<int> > P( H+2, vector<int>(W+2, 0) );

    for ( int i = 1; i <= H; i++ ) {
        string s;
        cin >> s;
        for ( int j = 1; j <= W; j++ ) {
            P[i][j] = s[j-1]-'0';
        }
    }

    double ans = DBL_MAX;
    for ( int i = 1; i <= W; i++ ) {
        
        double a,b;
        a = b = 0;

        for ( int y = 1; y <= H; y++ ) {
        for ( int x = 1; x <= W; x++ ) {

            if ( P[y][x] ) {
                a += sqrt( (x-i)*(x-i)+y*y );
                b += sqrt( (x-i)*(x-i)+(y-(H+1))*(y-(H+1)) );
            }
        }
        }

        ans = min( ans, min(a,b) );

    }

    for ( int i = 1; i <= H; i++ ) {
        
        double a,b;
        a = b = 0;

        for ( int y = 1; y <= H; y++ ) {
        for ( int x = 1; x <= W; x++ ) {
            if ( P[y][x] ) {
                a += sqrt( x*x+(y-i)*(y-i) );
                b += sqrt( (x-(W+1))*(x-(W+1))+(y-i)*(y-i) );
            }
        }
        }

        ans = min( ans, min(a,b) );

    }

    printf( "%.9f\n", ans );



    return 0;
}