#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], eating_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, bool is_mecho){
if (x >= 0 && x < n && y >= 0 && y < n){
if (is_mecho && (field[x][y] == 'G' || field[x][y] == 'D' || field[x][y] == 'M'))
return true;
else if (!is_mecho && (field[x][y] == 'G' || field[x][y] == 'M'))
return true;
return false;
}
return false;
}
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 = n*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));
//move bees
for (auto i : hives){
bees_q.push({i.first, i.second});
bees_visited[i.first][i.second] = true;
}
while (!bees_q.empty()){
int x = bees_q.front().first, y = bees_q.front().second;
bees_q.pop();
for (int i = 0; i < 4; i++){
int nx = x + dx[i], ny = y + dy[i];
if (valid_sq(nx, ny, false) && !bees_visited[nx][ny]){
if (eating_dis[x][y] < eating_time){
eating_dis[nx][ny] = eating_dis[x][y] + 1;
}else{
bees_dis[nx][ny] = bees_dis[x][y] + 1;
eating_dis[nx][ny] = INT_MAX;
}
bees_q.push({nx, ny});
bees_visited[nx][ny] = true;
}
}
}
mecho_q.push({startx, starty});
mecho_visited[startx][starty] = true;
while (!mecho_q.empty()){
int x = mecho_q.front().first, y = mecho_q.front().second;
mecho_q.pop();
for (int i = 0; i < 4; i++){
int nx = x + dx[i], ny = y + dy[i];
if (valid_sq(nx, ny, true) && !mecho_visited[nx][ny] && (mecho_dis[x][y] + 1) / s < bees_dis[nx][ny]){
mecho_visited[nx][ny] = true;
mecho_q.push({nx, ny});
mecho_dis[nx][ny] = mecho_dis[x][y] + 1;
}
}
}
bool mecho_reached = false;
for (int i = 0; i < 4; i++){
int nx = home_x+ dx[i], ny = home_y + dy[i];
if (valid_sq(nx, ny, true)){
if (bees_dis[nx][ny] > (mecho_dis[nx][ny] / s) && mecho_visited[nx][ny]){
mecho_reached = true;
break;
}
}
}
if (mecho_reached)
l = eating_time + 1;
else
r = eating_time - 1;
}
cout << l - 1 << '\n';
}
