#include<iostream>
#include<vector>
#include<queue>
using namespace std;
int N, M;
int arr[10][10];
int visited[10][10];
int dy[4] = { -1,1,0,0 };
int dx[4] = { 0,0,-1,1 };
vector<pair<int, int>> pos[7];
vector<pair<int, int>> list[7];
int vect[7];
struct node {
int start;
int end;
int dist;
};
struct cmp {
bool operator()(node right, node left) {
return left.dist < right.dist;
}
};
int find(int num) //부모 찾기
{
if (vect[num] == num) return num;
return vect[num] = find(vect[num]);
}
void Union(int a, int b) //같은 부모를 가지고 있는지
{
int pa = find(a);
int pb = find(b);
vect[pb] = pa;
}
void getDist(int a, int b) //두 섬 사이의 최단 거리 구하기
{
int ret = 987654321;
for (auto A : pos[a]) {
for (auto B : pos[b]) {
if (A.first == B.first) {
bool flag = false;
if (A.second > B.second) {
for (int i = B.second + 1; i < A.second; i++) {
if (arr[A.first][i] == 1) {
flag = true;
break;
}
}
if (flag == false) {
if (A.second - B.second - 1 != 1) {
ret = min(ret, A.second - B.second - 1);
}
}
}
else {
for (int i = A.second + 1; i < B.second; i++) {
if (arr[A.first][i] == 1) {
flag = true;
break;
}
}
if (flag == false) {
if (B.second - A.second - 1 != 1) {
ret = min(ret, B.second - A.second - 1);
}
}
}
}
if (A.second == B.second) {
bool flag = false;
if (A.first > B.first) {
for (int i = B.first + 1; i < A.first; i++) {
if (arr[i][A.second] == 1) {
flag = true;
break;
}
}
if (flag == false) {
if (A.first - B.first - 1 != 1) {
ret = min(ret, A.first - B.first - 1);
}
}
}
else {
for (int i = A.first + 1; i < B.first; i++) {
if (arr[i][A.second] == 1) {
flag = true;
break;
}
}
if (flag == false) {
if (B.first - A.first - 1 != 1) {
ret = min(ret, B.first - A.first - 1);
}
}
}
}
}
}
if (ret != 987654321) {
list[a].push_back({ b,ret });
}
}
void bfs(int y, int x, int cnt) //이어져 있는 땅 찾기
{
queue<pair<int, int>> q;
q.push({ y,x });
visited[y][x] = 1;
pos[cnt].push_back({ y,x });
while (!q.empty()) {
int y = q.front().first;
int x = q.front().second;
q.pop();
for (int i = 0; i < 4; i++) {
int yy = y + dy[i];
int xx = x + dx[i];
if (yy >= 0 && yy < N && xx >= 0 && xx < M) {
if (visited[yy][xx] != 1 && arr[yy][xx] == 1) {
visited[yy][xx] = 1;
q.push({ yy,xx });
pos[cnt].push_back({ yy,xx });
}
}
}
}
}
int main()
{
scanf("%d %d", &N, &M);
for (int i = 0; i < N; i++) {
for (int j = 0; j < M; j++) {
scanf("%d", &arr[i][j]);
}
}
int cnt = 1;
for (int i = 0; i < N; i++) {
for (int j = 0; j < M; j++) {
if (arr[i][j] == 1 && visited[i][j] != 1) {
bfs(i, j, cnt);
cnt++;
}
}
}
cnt;
for (int i = 1; i < cnt; i++) {
vect[i] = i;
for (int j = 1; j < cnt; j++) {
if (i != j) {
getDist(i, j);
}
}
}
priority_queue<node, vector<node>, cmp> pq;
for (int i = 1; i < cnt; i++) {
for (auto next : list[i]) {
pq.push({ i,next.first,next.second });
}
}
int ans = 0;
while (!pq.empty()) {
int start = pq.top().start;
int end = pq.top().end;
int dist = pq.top().dist;
pq.pop();
if (find(start) != find(end)) {
Union(start, end);
ans += dist;
}
}
for (int i = 1; i < cnt; i++) {
for (int j = 1; j < cnt; j++) {
if (i != j) {
if (find(i) != find(j)) {
printf("%d", -1);
return 0;
}
}
}
}
printf("%d", ans);
}
