#include <bits/stdc++.h>
using namespace std;
const int maxn = 805;
int n, s, b[maxn][maxn], m[maxn][maxn];
int dr[] = {0, 0, -1, 1};
int dc[] = {-1, 1, 0, 0};
char grid[maxn][maxn];
pair<int, int> st;
vector<pair<int, int>> hives;
bool check(int r, int c){
return 0 <= r && r < n && 0 <= c && c < n;
}
bool ok(int t){
memset(b, -1, sizeof b);
memset(m, -1, sizeof m);
queue<pair<int, int>> q;
for(auto x: hives){
q.push(x);
b[x.first][x.second] = 0;
}
while(!q.empty()){
auto[r, c] = q.front();
if(b[r][c]==t) break;
q.pop();
for(int i = 0; i < 4; i++){
int r2 = r + dr[i];
int c2 = c + dc[i];
if(check(r2, c2) && (grid[r2][c2] == 'M' || grid[r2][c2]=='G')&&b[r2][c2]==-1){
b[r2][c2] = b[r][c] + 1;
q.emplace(r2, c2);
}
}
}
queue<pair<int, int>> pos_loc;
pos_loc.push(st);
m[st.first][st.second] = 0;
int t2 = t;
while(!pos_loc.empty()){
t2++;
while(!pos_loc.empty()){
auto[r, c] = pos_loc.front();
if(m[r][c]==(t2-t)*s)
break;
pos_loc.pop();
if(~b[r][c]) continue;
for(int i = 0; i < 4; i++){
int r2 = r + dr[i];
int c2 = c + dc[i];
if(check(r2, c2) && b[r2][c2] == -1 && m[r2][c2] == -1 && (grid[r2][c2] == 'G' || grid[r2][c2] == 'D')){
if(grid[r2][c2]=='D') return true;
m[r2][c2] = m[r][c] + 1;
pos_loc.emplace(r2, c2);
}
}
}
while(!q.empty()){
auto[r, c] = q.front();
if(b[r][c] == t2)break;
q.pop();
for(int i = 0; i < 4; i++){
int r2 = r + dr[i];
int c2 = c + dc[i];
if(check(r2, c2) && b[r2][c2] == -1 && (grid[r2][c2] == 'G' || grid[r2][c2] == 'M')){
b[r2][c2] = b[r][c] + 1;
q.emplace(r2, c2);
}
}
}
}
return false;
}
int main() {
ios::sync_with_stdio(0); cin.tie(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') st = {i, j};
else if(grid[i][j]=='H') hives.push_back(make_pair(i, j));
}
int ans = -1;
for(int u = int(1e6); u > 0; u /= 2) while(ans + u <= int(1e6) && ok(ans + u)) ans += u;
cout << ans;
}
