#include<bits/stdc++.h>
using namespace std;
const int MAXN = 808;
int n, s, fx, fy;
char g[MAXN][MAXN];
#define ff first
#define ss second
int dist[MAXN][MAXN], type[MAXN][MAXN];
//type: 0 -- grass, 1 -- mecho, 2 -- hive, 3 -- tree;
int dx[] = {0, 1, 0, -1},
dy[] = {1, 0, -1, 0};
bool inbound(int nx, int ny){
return 1<=nx && nx <= n && 1 <= ny && ny <= n;
}
queue<pair<int, int>> bq, mq;
void expandBee(){
if(bq.empty()) return;
int x = bq.front().ff, y = bq.front().ss;
int dini = dist[x][y];
while(!bq.empty()){
int x = bq.front().ff, y = bq.front().ss;
if(dist[x][y] > dini) break;
bq.pop();
for(int i = 0; i < 4; i++){
int nx = x+dx[i], ny = y+dy[i];
if(!inbound(nx, ny)) continue;
if(type[nx][ny] > 1) continue;
type[nx][ny] = 2;
dist[nx][ny] = dist[x][y]+1;
bq.push({nx, ny});
}
}
}
void expandMecho(){
if(mq.empty()) return;
int x = mq.front().ff, y = mq.front().ss;
int dini = dist[x][y];
while(!mq.empty()){
int x = mq.front().ff, y = mq.front().ss;
if(dist[x][y] >= dini+s) break;
mq.pop();
if(type[x][y] > 1) continue;
for(int i = 0; i < 4; i++){
int nx = x+dx[i], ny = y+dy[i];
if(!inbound(nx, ny)) continue;
if(type[nx][ny] > 0) continue;
type[nx][ny] = 1;
dist[nx][ny] = dist[x][y]+1;
mq.push({nx, ny});
}
}
}
bool guess(int m){
while(mq.size()) mq.pop();
while(bq.size()) bq.pop();
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
dist[i][j] = 0;
if(g[i][j] == 'D') type[i][j] = 0;
else if(g[i][j] == 'G') type[i][j] = 0;
else if(g[i][j] == 'M') type[i][j] = 1, mq.push({i, j});
else if(g[i][j] == 'H') type[i][j] = 2, bq.push({i, j});
else if(g[i][j] == 'T') type[i][j] = 3;
}
}
for(int i = 1; i <= m; i++){
expandBee();
if(dist[fx][fy]) return false;
}
while(!dist[fx][fy]){
expandMecho();
if(dist[fx][fy]) return true;
expandBee();
}
return false;
}
int main(){
cin >> n >> s;
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++){
cin >> g[i][j];
if(g[i][j] == 'D') fx = i, fy = j;
}
if(!guess(0)){
cout << -1;
return 0;
}
int l = 0, r = 2000;
while(l < r){
int m = (l+r+1)/2;
if(guess(m)) l = m;
else r = m-1;
}
cout << l << '\n';
}
