#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int H,W; cin >> H >> W;
    vector<string> P(H);
    rep(i,H) cin >> P[i];

    using ld = long double;
    ld ans = 1e18;
    for(int x = 0; x <= H + 1; x++) {
        for(int y = 0; y <= W + 1; y++) {
            int cnt = (x == 0) + (x == H + 1) + (y == 0) + (y == W + 1);
            if(cnt == 1) {
                ld cost = 0;
                rep(i,H)rep(j,W)if(P[i][j] == '1') {
                    cost += sqrtl((x - (i+1)) * (x - (i+1)) + (y - (j+1)) * (y - (j+1)));
                }
                ans = min(ans, cost);
            }
        }
    }

    cout << fixed << setprecision(20) << ans << endl;
}