#include <bits/stdc++.h>
#define sz(x) (int)x.size()
#define x first
#define y second
#define X 0
#define Y 1
#define TIME 2
#define STEPS 3
using namespace std;
typedef pair<int, int> pi;
const int MX = 805;
string grid[MX];
int bees_time[MX][MX];
int N, S;
vector<pi> hives;
vector<pi> dirs = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
void calc_bee_times()
{
queue<pi> q;
for (auto i : hives)
{
q.push(i);
bees_time[i.x][i.y] = 0;
}
while (!q.empty())
{
auto curr = q.front();
q.pop();
for (auto d : dirs)
{
int i = curr.x + d.x, j = curr.y + d.y;
if (i < 0 || i >= N || j < 0 || j >= N || grid[i][j] == 'T' || grid[i][j] == 'D' || bees_time[i][j] != -1)
continue;
bees_time[i][j] = bees_time[curr.x][curr.y] + 1;
q.push({i, j});
}
}
}
pi mecho, home;
int processed[MX][MX];
bool ok(int t)
{
for (int i = 0; i < N; i++)
{
for (int j = 0; j < N; j++)
processed[i][j] = -1;
}
if (bees_time[mecho.x][mecho.y] <= t)
return false;
queue<pi> q;
processed[mecho.x][mecho.y] = 0;
q.push(mecho);
while (!q.empty())
{
auto curr = q.front();
// cout << "new queue top = " << curr.x << " " << curr.y << ", d=" << processed[curr.x][curr.y] << '\n';
q.pop();
for (auto d : dirs)
{
int i = curr.x + d.x, j = curr.y + d.y;
if (i < 0 || i >= N || j < 0 || j >= N || grid[i][j] == 'T' || (bees_time[i][j] <= t + (processed[curr.x][curr.y] + 1) / S && make_pair(i, j) != home) || processed[i][j] != -1)
continue;
// cout << "we can go to " << i << ", " << j << " from here with steps = " << processed[curr.x][curr.y] + 1 << ", moves = " << (processed[curr.x][curr.y] + 1) / S << '\n';
processed[i][j] = processed[curr.x][curr.y] + 1;
q.push({i, j});
}
}
return processed[home.x][home.y] != -1;
}
int main()
{
cin >> N >> S;
for (int i = 0; i < MX; i++)
for (int j = 0; j < MX; j++)
bees_time[i][j] = -1;
for (int i = 0; i < N; i++)
{
cin >> grid[i];
for (int j = 0; j < N; j++)
{
if (grid[i][j] == 'H')
hives.push_back({i, j});
else if (grid[i][j] == 'M')
mecho.x = i, mecho.y = j;
else if (grid[i][j] == 'D')
home.x = i, home.y = j;
}
}
calc_bee_times();
// cout << ok(2) << '\n';
// for (int i = 0; i < N; i++)
// {
// for (int j = 0; j < N; j++)
// cout << bees_time[i][j] << " ";
// cout << '\n';
// }
int lo = 0, hi = 800 * 800;
for (int b = hi / 2; b >= 1; b /= 2)
{
while (lo + b < hi && ok(lo + b))
lo += b;
}
if (lo == 0 && !ok(0))
cout << -1 << '\n';
else
cout << lo << '\n';
return 0;
}
