#include "bits/stdc++.h"
using namespace std;
const int N = 25;
vector<int> edges[N * N], cycle, path;
int used[N * N], cntv, cnte;
map<array<int, 4>, int> mem;
int rec(int i, int j, int left, int t)
{
if (i + 1 == (int)cycle.size() && j + 1 == (int)path.size())
return left;
if (mem.count({i, j, left, t}))
return mem[{i, j, left, t}];
int &res = mem[{i, j, left, t}];
res = -(1e9 + 7);
if (t == 0 && left >= 4)
res = max(res, left - 4 - rec(i, j, 4, -1));
if (t == 1 && left > 2)
res = max(res, left - 2 - rec(i, j, 2, -1));
if (i + 1 < (int)cycle.size())
res = max(res, left - rec(i + 1, j, cycle[i + 1], 0));
if (j + 1 < (int)path.size())
res = max(res, left - rec(i, j + 1, path[j + 1], 1));
return res;
}
void dfs(int u)
{
used[u] = 1;
cntv++;
cnte += (int)edges[u].size();
for (auto x : edges[u])
{
if (used[x])
continue;
dfs(x);
}
}
signed main()
{
int n, m;
cin >> n >> m;
vector<string> h(n + 1), v(n);
for (int i = 0; i < n + 1; i++)
cin >> h[i];
for (int i = 0; i < n; i++)
cin >> v[i];
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
int u = i * m + j;
if (i && h[i][j] == '0')
edges[u].push_back(u - m);
if (i + 1 < n && h[i + 1][j] == '0')
edges[u].push_back(u + m);
if (j && v[i][j] == '0')
edges[u].push_back(u - 1);
if (j + 1 < m && v[i][j + 1] == '0')
edges[u].push_back(u + 1);
if (h[i][j] == '1' && h[i + 1][j] == '1' && v[i][j] == '1' && v[i][j + 1] == '1')
used[i * m + j] = 1;
}
}
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
int u = i * m + j;
if (used[u])
continue;
cnte = cntv = 0;
dfs(u);
if (cntv * 2 > cnte)
path.push_back(cntv);
else
cycle.push_back(cntv);
}
}
sort(path.begin(), path.end());
sort(cycle.begin(), cycle.end());
cout << rec(-1, -1, 0, -1) << "\n";
}
