#include <bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define xx first
#define yy second
using namespace std;
typedef long long i64;
typedef pair<int,int> pii;
int n;
int s;
char gazar[810][810];
bool vis[810][810];
int beed[810][810];
int mei, mej;
bool feasible (int x){
memset(vis, 0, sizeof vis);
queue<pii> q;
int depth = x * s;
q.push(mp(mei, mej));
vis[mei][mej] = 1;
while(!q.empty()){
int sz = q.size();
for (int cnt = 0; cnt < sz; cnt++){
pii nw = q.front();
if (gazar[nw.xx][nw.yy] == 'D') return 1;
q.pop();
if (nw.xx < n && !vis[nw.xx + 1][nw.yy] && (gazar[nw.xx + 1][nw.yy] == 'D' || (gazar[nw.xx + 1][nw.yy] == 'G' && ((depth+1) / s) < beed[nw.xx + 1][nw.yy]) ) ) q.push(mp(nw.xx + 1, nw.yy)), vis[nw.xx + 1][nw.yy] = 1;
if (nw.xx > 1 && !vis[nw.xx - 1][nw.yy] && (gazar[nw.xx - 1][nw.yy] == 'D' || (gazar[nw.xx - 1][nw.yy] == 'G' && ((depth+1) / s) < beed[nw.xx - 1][nw.yy]) ) ) q.push(mp(nw.xx - 1, nw.yy)), vis[nw.xx - 1][nw.yy] = 1;
if (nw.yy < n && !vis[nw.xx][nw.yy + 1] && (gazar[nw.xx][nw.yy + 1] == 'D' || (gazar[nw.xx][nw.yy + 1] == 'G' && ((depth+1) / s) < beed[nw.xx][nw.yy + 1]) ) ) q.push(mp(nw.xx, nw.yy + 1)), vis[nw.xx][nw.yy + 1] = 1;
if (nw.yy > 1 && !vis[nw.xx][nw.yy - 1] && (gazar[nw.xx][nw.yy - 1] == 'D' || (gazar[nw.xx][nw.yy - 1] == 'G' && ((depth+1) / s) < beed[nw.xx][nw.yy - 1]) ) ) q.push(mp(nw.xx, nw.yy - 1)), vis[nw.xx][nw.yy - 1] = 1;
}
depth ++;
}
return 0;
}
int main (){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
// freopen("in.txt", "r", stdin);
cin >> n;
cin >> s;
for (int i = 1; i <= n; i++){
string tmp;
cin >> tmp;
// cout << tmp;
for (int j = 1; j <= n; j++){
gazar[i][j] = tmp[j - 1];
if (tmp[j - 1] == 'M') mei = i, mej = j;
}
}
queue<pii> q;
for (int i = 1; i <= n; i++){
for (int j = 1; j <= n; j++){
if (gazar[i][j] == 'H') q.push( mp(i, j) ), vis[i][j] = 1;
}
}
int depth = 0;
// cout << "QQQ";
while (!q.empty()){
int sz = q.size();
// cout << sz << ' ';
for (int cnt = 0; cnt < sz; cnt++){
pii nw = q.front();
q.pop();
beed[nw.xx][nw.yy] = depth;
if (nw.xx < n && !vis[nw.xx + 1][nw.yy] && (gazar[nw.xx + 1][nw.yy] == 'M' || gazar[nw.xx + 1][nw.yy] == 'G') ) q.push(mp(nw.xx + 1, nw.yy)), vis[nw.xx + 1][nw.yy] = 1;
if (nw.xx > 1 && !vis[nw.xx - 1][nw.yy] && (gazar[nw.xx - 1][nw.yy] == 'M' || gazar[nw.xx - 1][nw.yy] == 'G') ) q.push(mp(nw.xx - 1, nw.yy)), vis[nw.xx - 1][nw.yy] = 1;
if (nw.yy < n && !vis[nw.xx][nw.yy + 1] && (gazar[nw.xx][nw.yy + 1] == 'M' || gazar[nw.xx][nw.yy + 1] == 'G') ) q.push(mp(nw.xx, nw.yy + 1)), vis[nw.xx][nw.yy + 1] = 1;
if (nw.yy > 1 && !vis[nw.xx][nw.yy - 1] && (gazar[nw.xx][nw.yy - 1] == 'M' || gazar[nw.xx][nw.yy - 1] == 'G') ) q.push(mp(nw.xx, nw.yy - 1)), vis[nw.xx][nw.yy - 1] = 1;
}
depth++;
}
int lo = 0, hi = beed[mei][mej] - 1;
while (lo != hi){
int mid = (lo + hi + 1) >> 1;
if (feasible(mid)) lo = mid;
else hi = mid - 1;
}
if(feasible(lo)) cout << lo;
else cout << -1;
return 0;
}
