#include <bits/stdc++.h>
using namespace std;
#define pi pair<int, int>
#define f first
#define s second
int N, S;
const int MN = 800;
char grid[MN][MN] = {{}};
vector<pi> hives;
pi M; pi D;
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
void movebees(queue<pi> (&b), char (&v)[MN][MN], int t){
for(int i = 0; i < t; i++){
queue<pi> nextb;
while(!b.empty()){
pi p = b.front(); b.pop();
for(int d = 0; d < 4; d++){
int nx = p.f + dx[d]; int ny = p.s + dy[d];
if(nx < 0 || nx >= N || ny < 0 || ny >= N) continue;
if(v[nx][ny] != 'B' && grid[nx][ny] == 'G'){
v[nx][ny] = 'B';
nextb.push({nx, ny});
}
}
}
b = nextb;
}
}
bool movemecho(queue<pi> (&m), char (&v)[MN][MN]){
for(int i = 0; i < S; i++){
queue<pi> nextm;
while(!m.empty()){
pi p = m.front(); m.pop();
for(int d = 0; d < 4; d++){
int nx = p.f + dx[d]; int ny = p.s + dy[d];
if(nx < 0 || nx >= N || ny < 0 || ny >= N) continue;
if(!v[nx][ny] && grid[nx][ny] != 'T'){
if(grid[nx][ny] == 'D') return true;
v[nx][ny] = 'M';
nextm.push({nx, ny});
}
}
}
m = nextm;
}
return false;
}
bool works(int t){ //O(N^2)
char visited[MN][MN] = {{}};
queue<pi> bees;
for(pi p : hives){
bees.push(p);
visited[p.first][p.second] = 'B';
}
movebees(bees, visited, t);
queue<pi> mecho; mecho.push(M); visited[M.f][M.s] = 'M';
for(int i = 0; i < N*N/2; i++){
//first, move mecho S steps
if(mecho.empty()) break;
bool success = movemecho(mecho, visited);
if(success) return true;
//then, move bees 1 step
movebees(bees, visited, 1);
}
return false;
}
int main(){
cin.tie(0)->sync_with_stdio(0);
cin >> N >> S;
for(int i = 0; i < N; i++){
for(int j = 0; j < N; j++){
cin >> grid[i][j];
if(grid[i][j] == 'M') M = {i, j};
if(grid[i][j] == 'D') D = {i, j};
if(grid[i][j] == 'H') hives.push_back({i,j});
}
}
int lo = -1; int hi = N*N/2; //amount of head start to bees
while(lo < hi){ // in total, O(N^2 log N)
int mid = lo + (hi - lo + 1) / 2;
if(works(mid)){
lo = mid;
} else {
hi = mid - 1;
}
}
cout << lo;
return 0;
}
