#include <bits/stdc++.h>
#define fi first
#define se second
#define int long long
using namespace std;
using ll = long long;
using ii = pair<int,int>;
using pii = pair<int,ii>;
using aa = array<int,4>;
const int N = 805;
const int INF = 1e9;
const int MOD = 1e9+21;
int n,S,c,u,v,start_x,start_y,home_x,home_y;
int ans = -1,cur = -1;
int Mecho[N][N],Bee[N][N];
bool vis[N][N],okay;
int dx[4] = {1,0,-1,0};
int dy[4] = {0,1,0,-1};
char a[N][N];
queue <ii> q;
bool reached(int a,int b){
return a / S < b;
}
bool ok(int i,int j){
return min(i,j) >= 1 && max(i,j) <= n && a[i][j] != 'H' && a[i][j] != 'T';
}
bool check(int mid){
while (!q.empty()) q.pop();
q.push({start_x,start_y});
if (!reached(0,Bee[start_x][start_y] - mid)) return 0;
Mecho[start_x][start_y] = 0;
okay = 0;
for (int i = 1; i <= n; i++){
for (int j = 1; j <= n; j++) vis[i][j] = 0;
}
vis[start_x][start_y] = 1;
while (!q.empty()){
tie(u,v) = q.front();
if (u == home_x && v == home_y) return 1;
q.pop();
for (int k = 0; k < 4; k++){
int x = u + dx[k];
int y = v + dy[k];
if (ok(x,y) && !vis[x][y] && reached(Mecho[u][v]+1,Bee[x][y] - mid)){
Mecho[x][y] = Mecho[u][v] + 1;
vis[x][y] = 1;
q.push({x,y});
}
}
}
return 0;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
cin >> n >> S;
for (int i = 1; i <= n; i++){
for (int j = 1; j <= n; j++){
cin >> a[i][j];
if (a[i][j] == 'M'){ //Mecho pos
start_x = i;
start_y = j;
}
if (a[i][j] == 'H'){ //Hives pos
q.push({i,j});
vis[i][j] = 1;
}
if (a[i][j] == 'D'){ //Mecho home
home_x = i;
home_y = j;
Bee[i][j] = 1e9+5;
}
}
}
while (!q.empty()){
tie(u,v) = q.front();
q.pop();
for (int k = 0; k < 4; k++){
int x = u + dx[k];
int y = v + dy[k];
if (ok(x,y) && !vis[x][y] && a[x][y] != 'D'){
Bee[x][y] = Bee[u][v] + 1;
vis[x][y] = 1;
q.push({x,y});
}
}
}
int l = 0,r = n*n,ans = -1;
while(l <= r){
int mid = (l + r) >> 1;
if (check(mid)){
ans = mid;
l = mid + 1;
} else r = mid - 1;
}
cout << ans;
return 0;
}
