#include <bits/stdc++.h>
using namespace std;
int N, S;
char arr[810][810];
int sx, sy, ex, ey;
typedef pair<int, int> pii;
#define f first
#define s second
queue<pair<pii, int> > q1;
queue<pair<pii, int> > q2;
int vis1[810][810];
int vis2[810][810];
const int INF = 0x3f3f3f3f;
int xd[4] = {1, -1, 0, 0};
int yd[4] = {0, 0, 1, -1};
void bfs(int t){
while (!q2.empty()){
int x = q2.front().f.f;
int y = q2.front().f.s;
int w = q2.front().s;
if (w == t)
break;
q2.pop();
for (int k = 0; k < 4; k++){
int nx = x+xd[k];
int ny = y+yd[k];
if (nx >= 1 && nx <= N && ny >= 1 && ny <= N &&
arr[nx][ny] != 'T' && arr[nx][ny] != 'D'){
if (vis2[nx][ny] > vis2[x][y]+1){
vis2[nx][ny] = vis2[x][y]+1;
q2.push({{nx, ny}, vis2[nx][ny]});
}
}
}
}
}
bool valid(int t){
while (!q1.empty()) q1.pop();
while (!q2.empty()) q2.pop();
memset(vis1, INF, sizeof(vis1));
memset(vis2, INF, sizeof(vis2));
for (int i = 1; i <= N; i++){
for (int j = 1; j <= N; j++){
if (arr[i][j] == 'H'){
q2.push({{i, j}, 0});
vis2[i][j] = 0;
}
}
}
q1.push({{sx, sy}, 0});
vis1[sx][sy] = 0;
int curtime = 1;
while (curtime <= t){
bfs(curtime);
curtime++;
}
while (!q1.empty()){
int x = q1.front().f.f;
int y = q1.front().f.s;
int w = q1.front().s;
if (x == ex && y == ey){
return true;
}
if (vis1[x][y] == (curtime-t)*S){
bfs(curtime);
curtime++;
}
q1.pop();
if (vis2[x][y] != INF){
continue;
}
for (int k = 0; k < 4; k++){
int nx = x+xd[k];
int ny = y+yd[k];
if (nx >= 1 && nx <= N && ny >= 1 && ny <= N && vis2[nx][ny] == INF &&
(arr[nx][ny] == 'D' || arr[nx][ny] == 'G')){
if (vis1[nx][ny] > vis1[x][y]+1){
vis1[nx][ny] = vis1[x][y]+1;
q1.push({{nx, ny}, vis1[nx][ny]});
}
}
}
}
return false;
}
int main(){
cin >> N >> S;
for (int i = 1; i <= N; i++){
for (int j = 1; j <= N; j++){
cin >> arr[i][j];
if (arr[i][j] == 'M'){
sx = i;
sy = j;
}
if (arr[i][j] == 'D'){
ex = i;
ey = j;
}
}
}
if (!valid(0)){
cout << -1 << "\n";
return 0;
}
int l = 0, r = 640000;
while (l != r){
int mid = (l+r+1)/2;
if (valid(mid)){
l = mid;
} else {
r = mid-1;
}
}
cout << l << "\n";
}
