#include <bits/stdc++.h>
using namespace std;
template<typename T> void dout(string name, T arg) {
cerr << name << " = " << arg << "\e[39m" << endl;
}
template<typename T1, typename... T2> void dout(string names, T1 arg, T2... args) {
cerr << names.substr(0, names.find(',')) << " = " << arg << " | ";
dout(names.substr(names.find(',') + 2), args...);
}
#define debug(...) cerr << "\e[91m" << "[" << __LINE__ << ":" << __func__ << "]=> ", dout(#__VA_ARGS__, __VA_ARGS__);
const int N = 800;
vector<string> field(N);
int n, s;
bool valid(int x, int y) {
return x >= 0 && x < n && y >= 0 && y < n && (field[x][y] == 'G' || field[x][y] == 'M');
}
bool reached(int m, int b) {
return m / s < b;
}
int main() {
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n >> s;
for (int i = 0; i < n; i++) {
cin >> field[i];
}
vector<pair<int, int>> hives;
pair<int, int> m, d;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
if (field[i][j] == 'M') {
m = {i, j};
}
if (field[i][j] == 'H') {
hives.push_back({i, j});
}
if (field[i][j] == 'D') {
d = {i, j};
}
}
}
int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, -1, 0, 1};
int l = 0, r = n * n;
while (l <= r) {
vector<vector<bool>> bees_visited(n, vector<bool>(n));
vector<vector<bool>> mecho_visited(n, vector<bool>(n));
vector<vector<int>> bees_time(n, vector<int>(n));
vector<vector<int>> mecho_time(n, vector<int>(n));
queue<pair<int, int>> q;
int mid = (l + r) / 2;
for (auto [x, y] : hives) {
q.push({x, y});
bees_visited[x][y] = true;
}
while (!q.empty()) {
auto [x, y] = q.front();
q.pop();
for (int i = 0; i < 4; i++) {
int xx = x + dx[i], yy = y + dy[i];
if (valid(xx, yy) && !bees_visited[xx][yy]) {
bees_time[xx][yy] = bees_time[x][y] + 1;
q.push({xx, yy});
bees_visited[xx][yy] = true;
}
}
}
q.push(m);
mecho_visited[m.first][m.second] = true;
if (bees_time[m.first][m.second] <= mid) {
q.pop();
}
while (!q.empty()) {
auto [x, y] = q.front();
q.pop();
for (int i = 0; i < 4; i++) {
int xx = x + dx[i], yy = y + dy[i];
if (valid(xx, yy) && !mecho_visited[xx][yy] && reached(mecho_time[x][y] + 1, bees_time[xx][yy] - mid)) {
mecho_time[xx][yy] = mecho_time[x][y] + 1;
q.push({xx, yy});
mecho_visited[xx][yy] = true;
}
}
}
bool reach = false;
for (int i = 0; i < 4; i++) {
int xx = d.first + dx[i], yy = d.second + dy[i];
if (valid(xx, yy) && reached(mecho_time[xx][yy], bees_time[xx][yy] - mid) && mecho_visited[xx][yy]) {
reach = true;
}
}
if (reach) {
l = mid + 1;
}
else {
r = mid - 1;
}
}
cout << l - 1 << '\n';
return 0;
}
