H,W = map(int, input().split())
P = [input() for _ in range(H)]

def dist(x, y, s, t):
    return ((x-s)**2+(y-t)**2)**0.5

ans = 10**9
for i in range(-1, H+1, H+1):
    for j in range(W):
        num = 0
        for k in range(H):
            for l in range(W):
                if P[k][l] == "0":
                    continue
                num += dist(i, j, k, l)
        ans = min(ans, num)

for j in range(-1, W+1, W+1):
    for i in range(H):
        num = 0
        for k in range(H):
            for l in range(W):
                if P[k][l] == "0":
                    continue
                num += dist(i, j, k, l)
        ans = min(ans, num)
print(ans)