#include <iostream>
#include <vector>
#include <queue>
#include <climits>
using std::cout;
using std::endl;
using std::vector;
using std::pair;
vector<pair<int, int>> neighbors(const pair<int, int>& at, int row_num, int col_num) {
vector<pair<int, int>> neighbors;
if (at.first > 0) {
neighbors.push_back({at.first - 1, at.second});
}
if (at.second > 0) {
neighbors.push_back({at.first, at.second - 1});
}
if (at.first < row_num - 1) {
neighbors.push_back({at.first + 1, at.second});
}
if (at.second < col_num - 1) {
neighbors.push_back({at.first, at.second + 1});
}
return neighbors;
}
class Field {
private:
const vector<vector<char>> field;
const int row_num;
const int col_num;
pair<int, int> start;
vector<vector<int>> bee_dists;
public:
Field(const vector<vector<char>>& field)
: field(field), row_num(field.size()), col_num(field[0].size()),
bee_dists(row_num, vector<int>(col_num, INT_MAX)) {
std::queue<pair<int, int>> frontier;
for (int r = 0; r < row_num; r++) {
for (int c = 0; c < col_num; c++) {
if (field[r][c] == 'H') {
frontier.push({r, c});
bee_dists[r][c] = 0;
} else if (field[r][c] == 'M') {
start = {r, c};
}
}
}
while (!frontier.empty()) {
pair<int, int> c = frontier.front(); // c for curr and to reduce my line length
frontier.pop();
int n_cost = bee_dists[c.first][c.second] + 1;
for (const pair<int, int>& n : neighbors(c, row_num, col_num)) {
if (n_cost < bee_dists[n.first][n.second]
&& field[n.first][n.second] != 'T'
&& field[n.first][n.second] != 'D') {
bee_dists[n.first][n.second] = n_cost;
frontier.push(n);
}
}
}
}
bool can_go_home(int honey_time, int speed) {
if (bee_dists[start.first][start.second] <= honey_time) {
return false;
}
std::queue<pair<int, int>> frontier;
vector<vector<int>> min_moves(row_num, vector<int>(col_num, INT_MAX));
frontier.push(start); // dw, we checked if the start was valid literally above
min_moves[start.first][start.second] = honey_time * speed;
while (!frontier.empty()) {
pair<int, int> curr = frontier.front();
frontier.pop();
if (field[curr.first][curr.second] == 'D') {
return true;
}
int n_cost = min_moves[curr.first][curr.second] + 1;
for (const pair<int, int>& n : neighbors(curr, row_num, col_num)) {
if (field[n.first][n.second] != 'T'
&& (n_cost / speed) < bee_dists[n.first][n.second]
&& n_cost < min_moves[n.first][n.second]) {
min_moves[n.first][n.second] = n_cost;
frontier.push(n);
}
}
}
return false;
}
};
// https://oj.uz/problem/view/IOI09_mecho (sample input ommitted)
int main() {
int side_len;
int speed;
std::cin >> side_len >> speed;
vector<vector<char>> grid(side_len, vector<char>(side_len));
for (int r = 0; r < side_len; r++) {
for (int c = 0; c < side_len; c++) {
std::cin >> grid[r][c];
}
}
Field field(grid);
int lo = 0;
int hi = side_len * side_len;
int valid = -1;
while (lo <= hi) {
int mid = (lo + hi) / 2;
if (field.can_go_home(mid, speed)) {
valid = mid;
lo = mid + 1;
} else {
hi = mid - 1;
}
}
cout << valid << endl;
}
