#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 800;
vector <string> field(MAX_N);
bool bees_visited[MAX_N][MAX_N], mecho_visited[MAX_N][MAX_N];
int mecho_dis[MAX_N][MAX_N], bees_dis[MAX_N][MAX_N];
queue <pair <int, int>> mecho_q, bees_q;
int dx[] = {-1, 1, 0, 0};
int dy[] = {0, 0, -1, 1};
int n, s;
bool valid_sq(int x, int y){
if (x >= 0 && x < n && y >= 0 && y < n && field[x][y] != 'T' && field[x][y] != 'H')
return true;
return false;
}
void update_field(queue <pair <int, int>> &q, int max_steps, bool (&visited)[MAX_N][MAX_N], bool (&visited2)[MAX_N][MAX_N], int (&dis)[MAX_N][MAX_N], bool is_mecho){
while (!q.empty() && dis[q.front().first][q.front().second] != -1){
int x = q.front().first, y = q.front().second;
q.pop();
if (is_mecho && visited2[x][y])
continue;
for (int i = 0; i < 4; i++){
if (valid_sq(x + dx[i], y + dy[i]) && !visited[x+dx[i]][y+dy[i]] && !visited2[x+dx[i]][y+dy[i]]){
q.push({x+dx[i], y+dy[i]});
visited[x+dx[i]][y+dy[i]] = true;
if (dis[x][y] + 1 < max_steps)
dis[x+dx[i]][y+dy[i]] = dis[x][y] + 1;
else
dis[x+dx[i]][y+dy[i]] = -1;
}
}
}
}
int main()
{
// freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
cin >> n >> s;
for (int i = 0; i < n; i++)
cin >> field[i];
vector <pair <int, int>> hives;
int startx, starty, home_x, home_y;
//find Mecho's position
for (int i = 0; i < n; i++){
for (int j = 0; j < n; j++){
if (field[i][j] == 'M'){
startx = i;
starty = j;
}else if (field[i][j] == 'H'){
hives.push_back({i, j});
}else if (field[i][j] == 'D'){
home_x = i;
home_y = j;
}
}
}
int l = 0, r = 2*n;
while (l <= r){
int eating_time = (l + r) / 2;
memset(bees_visited, false, sizeof(bees_visited));
memset(mecho_visited, false, sizeof(mecho_visited));
memset(bees_dis, 0, sizeof(bees_dis));
memset(mecho_dis, 0, sizeof(mecho_dis));
//simulate
for (auto i : hives){
bees_q.push({i.first, i.second});
bees_visited[i.first][i.second] = true;
}
if (eating_time > 0){
for (int i = 0; i < eating_time; i++)
update_field(bees_q, 1, bees_visited, bees_visited, bees_dis, false);
}
mecho_q.push({startx, starty});
for (int i = eating_time; i <= n*2-2 && !bees_q.empty() && !mecho_q.empty(); i++){
while (!bees_q.empty() && bees_dis[bees_q.front().first][bees_q.front().second] == -1){
bees_dis[bees_q.front().first][bees_q.front().second] = 0;
bees_q.push({bees_q.front().first, bees_q.front().second});
bees_q.pop();
}while (!mecho_q.empty() && mecho_dis[mecho_q.front().first][mecho_q.front().second] == -1){
mecho_dis[mecho_q.front().first][mecho_q.front().second] = 0;
mecho_q.push({mecho_q.front().first, mecho_q.front().second});
mecho_q.pop();
}
update_field(mecho_q, s, mecho_visited, bees_visited, mecho_dis, true);
if (mecho_visited[home_x][home_y])
break;
update_field(bees_q, 1, bees_visited, bees_visited, bees_dis, false);
}
if (mecho_visited[home_x][home_y])
l = eating_time + 1;
else
r = eating_time - 1;
//empty_queues
while (!bees_q.empty())
bees_q.pop();
while (!mecho_q.empty())
mecho_q.pop();
}
cout << l - 1 << '\n';
}
