#include <bits/stdc++.h>
using namespace std;
template<class A, class B> bool maximize(A& x, B y) {if (x < y) return x = y, true; else return false;}
template<class A, class B> bool minimize(A& x, B y) {if (x > y) return x = y, true; else return false;}
#define all(a) a.begin(), a.end()
#define pb push_back
#define pf push_front
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ld;
typedef pair<db, db> pdb;
typedef pair<ld, ld> pld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ll, int> plli;
typedef pair<int, ll> pill;
const int MAX_N = 800 + 5;
const int dx[] = {0, 0, 1, -1};
const int dy[] = {1, -1, 0, 0};
int n, S;
string a[MAX_N];
pii s, t;
int dist[MAX_N][MAX_N];
bool ok[MAX_N][MAX_N];
bool inside(int x, int y) {
return x > 0 && x <= n && y > 0 && y <= n;
}
bool check(int mid) {
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
ok[i][j] = false;
}
}
queue<pair<pii, int>> q;
q.push({s, mid + 1});
ok[s.fi][s.se] = true;
while (!q.empty()) {
int u = q.front().fi.fi;
int v = q.front().fi.se;
int time = q.front().se;
q.pop();
queue<pii> nxt_q;
for (int k = 0; k < 4; k++) {
int x = u + dx[k];
int y = v + dy[k];
if (inside(x, y) && (a[x][y] == 'G' || a[x][y] == 'D') && !ok[x][y] && dist[x][y] > time) {
ok[x][y] = true;
nxt_q.push({x, y});
if (time + 1 < dist[x][y]) {
q.push({{x, y}, time + 1});
}
}
}
while (!nxt_q.empty()) {
int nxt_u = nxt_q.front().fi;
int nxt_v = nxt_q.front().se;
nxt_q.pop();
if (abs(nxt_u - u) + abs(nxt_v - v) == S) {
continue;
}
for (int k = 0; k < 4; k++) {
int x = nxt_u + dx[k];
int y = nxt_v + dy[k];
if (inside(x, y) && (a[x][y] == 'G' || a[x][y] == 'D') && !ok[x][y] && dist[x][y] > time) {
ok[x][y] = true;
nxt_q.push({x, y});
if (time + 1 < dist[x][y]) {
q.push({{x, y}, time + 1});
}
}
}
}
}
// for (int i = 1; i <= n; i++) {
// for (int j = 1; j <= n; j++) {
// cout << ok[i][j] << " ";
// }
// cout << '\n';
// }
return ok[t.fi][t.se];
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
queue<pii> q;
cin >> n >> S;
for (int i = 1; i <= n; i++) {
cin >> a[i];
a[i] = ' ' + a[i];
for (int j = 1; j <= n; j++) {
if (a[i][j] == 'M') {
s = {i, j};
}
if (a[i][j] == 'D') {
t = {i, j};
}
if (a[i][j] == 'H') {
q.push({i, j});
dist[i][j] = 1;
}
}
}
dist[t.fi][t.se] = 1e9;
while (!q.empty()) {
int u = q.front().fi;
int v = q.front().se;
q.pop();
for (int k = 0; k < 4; k++) {
int x = u + dx[k];
int y = v + dy[k];
if (inside(x, y) && (a[x][y] == 'G' || a[x][y] == 'M') && !dist[x][y]) {
dist[x][y] = dist[u][v] + 1;
q.push({x, y});
}
}
}
// for (int i = 1; i <= n; i++) {
// for (int j = 1; j <= n; j++) {
// cout << dist[i][j] << " ";
// }
// cout << '\n';
// }
// cout << check(2);
// return 0;
int low = 0, high = dist[s.fi][s.se] - 2;
int ans = -1;
while (low <= high) {
int mid = (low + high) >> 1;
if (check(mid)) {
ans = mid;
low = mid + 1;
}
else {
high = mid - 1;
}
}
cout << ans;
return 0;
}
/*
*/
