#include <bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define vi vector<int>
#define vl vector<ll>
#define mp make_pair
#define pb push_back
using namespace std;
int n, s,sx, sy, ex, ey;
const int Nmax = 1000;
char mat[Nmax][Nmax];
int dist[Nmax][Nmax];
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
vector<pii> hives;
class state{
public:
int x;
int y;
int steps_made;
int cur_minute;
};
bool in_range(int i, int j){
if(i >= 0 && j >= 0 && i < n && j < n)
return true;
return false;
}
void calculate_dist(){
queue<vector<pii> > q;
q.push(hives);
while(!q.empty()){
vector<pii> current = q.front(); q.pop();
vector<pii> next_current;
for(int i = 0; i < current.size(); i++){
int x = current[i].first, y = current[i].second;
for(int dir = 0; dir < 4; dir++){
int nx = x + dx[dir], ny = y + dy[dir];
if(in_range(nx, ny) && mat[nx][ny] != 'T' && dist[nx][ny] == -1){
dist[nx][ny] = 1 + dist[x][y];
next_current.pb(mp(nx,ny));
}
}
}
if(next_current.size() > 0)
q.push(next_current);
}
}
bool solve(int minutes){
queue<state> q;
q.push({sx,sy,0,minutes+1});
bool finished = false;
bool vis[801][801];
memset(vis, false, sizeof(vis));
vis[sx][sy] = true;
while(!q.empty()){
state current = q.front(); q.pop();
int x = current.x, y = current.y, steps_made = current.steps_made, cur_minute = current.cur_minute;
//cout<<x<<" "<<y<<" "<<steps_made<<" "<<cur_minute<<endl;
if(steps_made == s){
steps_made = 0;
cur_minute++;
}
for(int dir = 0; dir < 4; dir++){
int nx = x + dx[dir], ny = y + dy[dir];
//cout<<dist[nx][ny]<<" "<<cur_minute<<endl;
if(in_range(nx,ny) && mat[nx][ny] != 'T' && !vis[nx][ny] && dist[nx][ny] >= cur_minute){
if(dist[nx][ny] == cur_minute && steps_made + 1 == s)
continue;
if(nx == ex && ny == ey){
finished = true;
break;
}
vis[nx][ny] = true;
q.push({nx, ny, steps_made + 1, cur_minute});
}
}
if(finished)
break;
}
return finished;
}
int main(){
cin>>n>>s;
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
cin>>mat[i][j];
if(mat[i][j] == 'M')
sx = i, sy = j;
if(mat[i][j] == 'D')
ex = i, ey = j;
if(mat[i][j] == 'H')
hives.pb(mp(i,j));
}
}
memset(dist, -1, sizeof(dist));
for(int i = 0; i < hives.size(); i++)
dist[hives[i].first][hives[i].second] = 0;
calculate_dist();
int l = 0, r = 10000, solution=-1;
while(l <= r){
int mid = (l + r) / 2;
bool sol = solve(mid);
if(sol){
solution = mid;
l = mid + 1;
}
else
r = mid - 1;
}
cout<<solution<<endl;
}
