#include <bits/stdc++.h>
using namespace std;
const int dx[4] = {1,0,-1,0}, dy[4] = {0,1,0,-1};
int n,s;
char str[805][805];
int vis[805][805];
int dep[805][805];
int sx, sy;
void bee(){
queue<int> qx, qy, d;
for (int i=0; i<n; i++) {
for (int j=0; j<n; j++) {
if(str[i][j] == 'H'){
qx.push(i);
qy.push(j);
d.push(0);
vis[i][j] = 1;
}
}
}
while (!qx.empty()){
int xf = qx.front();
int yf = qy.front();
int df = d.front();
qx.pop();
qy.pop();
d.pop();
dep[xf][yf] = df;
for (int i=0; i<4; i++) {
int nx = xf + dx[i];
int ny = yf + dy[i];
if(nx < 0 || ny < 0 || nx >= n || ny >= n) continue;
if(vis[nx][ny]) continue;
if(str[nx][ny] != 'G' && str[nx][ny] != 'M') continue;
vis[nx][ny] = 1;
qx.push(nx);
qy.push(ny);
d.push(df+1);
}
}
}
bool trial(int x){
memset(vis,0,sizeof(vis));
queue<int> qx, qy, d;
qx.push(sx);
qy.push(sy);
d.push(x * s);
vis[sx][sy] = 1;
while (!qx.empty()) {
int xf = qx.front();
int yf = qy.front();
int df = d.front();
qx.pop();
qy.pop();
d.pop();
if(str[xf][yf] == 'D') return 1;
for (int i=0; i<4; i++) {
int nx = xf + dx[i];
int ny = yf + dy[i];
if(nx < 0 || ny < 0 || nx >= n || ny >= n) continue;
if(vis[nx][ny]) continue;
if(str[nx][ny] != 'G' && str[nx][ny] !='D') continue;
if(str[nx][ny] != 'D' && (df+1) / s >= dep[nx][ny]) continue;
vis[nx][ny] = 1;
qx.push(nx);
qy.push(ny);
d.push(df+1);
}
}
return 0;
}
int main(){
cin >> n >> s ;
for (int i=0; i<n; i++) {
cin >> str[i];
for (int j=0; j<n; j++) {
if(str[i][j] == 'M') sx = i, sy = j;
}
}
bee();
int s = 0, e = dep[sx][sy]-1;
while (s != e) {
int m = (s+e+1)/2;
if(trial(m)) s = m;
else e = m-1;
}
if(trial(s)) cout << s << "\n";
else cout << "-1\n";
}
