#include <iostream>
#include <vector>
#include <queue>
#include <map>
using namespace std;
int main() {
int n, m;
cin >> n >> m;
vector<vector<int> > buttons(m, vector<int>(n));
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
cin >> buttons[i][j];
}
}
vector<int> start(n, 1);
vector<int> target(n, 0);
map<vector<int>, int> visited;
queue<pair<vector<int>, int> > q;
q.push(make_pair(start, 0));
visited[start] = 0;
while (!q.empty()) {
pair<vector<int>, int> current = q.front();
q.pop();
vector<int> state = current.first;
int steps = current.second;
// 检查是否达到目标状态
bool allOff = true;
for (int i = 0; i < n; i++) {
if (state[i] != 0) {
allOff = false;
break;
}
}
if (allOff) {
cout << steps << endl;
return 0;
}
for (int i = 0; i < m; i++) {
vector<int> newState = state;
for (int j = 0; j < n; j++) {
int effect = buttons[i][j];
if (effect == 1) {
if (newState[j] == 1) newState[j] = 0;
} else if (effect == -1) {
if (newState[j] == 0) newState[j] = 1;
}
}
if (visited.find(newState) == visited.end()) {
visited[newState] = steps + 1;
q.push(make_pair(newState, steps + 1));
}
}
}
cout << -1 << endl;
return 0;
}