#include <bits/stdc++.h>
using namespace std;
int main()
{
int n, m;
cin >> n >> m;
char arr[n + 5][m + 5];
for(int i = 0; i < n; i++)
{
for(int j = 0; j < m; j++)
{
cin >> arr[i][j];
}
}
int res = 0;
int sum = 0;
if(n == 1 || m == 1)
{
if(n == 1)
{
for(int i = 0; i < m; i++)
{
// cout << sum << " ";
if(arr[0][i] == '1')
{
sum++;
}
else
{
if(res == 0)res = sum;
else
{
res = min(res, sum);
}
sum = 0;
}
}
if(res == 0)res = sum;
else res = min(res, sum);
}
else if(m == 1)
{
for(int i = 0; i < n; i++)
{
// cout << sum << " ";
if(arr[i][0] == '1')
{
sum++;
}
else
{
if(res == 0)res = sum;
else
{
res = min(res, sum);
}
sum = 0;
}
}
if(res == 0)res = sum;
else res = min(res, sum);
}
}
cout << res << endl;
return 0;
}
