#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
using pi = pair<int, int>;
using vpi = vector<pi>;
const int N = 805;
int n, s, b[N][N], m[N][N];
int dr[] = {0, 0, -1, 1};
int dc[] = {-1, 1, 0, 0};
char a[N][N]; // the grid
pi st; // the starting position for mecho
vpi h; // locations of all of the bee hives
bool good(int r, int c){ // is cell (r, c) within bounds?
return 0 <= r && r < n && 0 <= c && c < n;
}
bool ok(int t){ // can the answer be t?
memset(b, -1, sizeof b);
memset(m, -1, sizeof m);
queue<pi> q; // all of the current bees' possible locations
for(auto x: h){
q.push(x);
b[x.ff][x.ss] = 0;
}
// the bees "expand" for t seconds
while(!q.empty()){ // bfs
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(good(r2, c2)&&(a[r2][c2]=='M'||a[r2][c2]=='G')&&b[r2][c2]==-1){
b[r2][c2] = b[r][c] + 1;
q.emplace(r2, c2);
}
}
}
queue<pi> q2; // mecho's possible locations
q2.push(st);
m[st.ff][st.ss] = 0;
int t2 = t;
while(!q2.empty()){
t2++;
// mecho's possible locations "expand" for 1 second (where he can take up to s steps)
while(!q2.empty()){ // bfs
auto[r, c] = q2.front();
if(m[r][c]==(t2-t)*s)
break;
q2.pop();
if(~b[r][c])
continue;
for(int i = 0; i < 4; ++i){
int r2 = r + dr[i];
int c2 = c + dc[i];
if(good(r2, c2)&&b[r2][c2]==-1&&m[r2][c2]==-1&&
(a[r2][c2]=='G'||a[r2][c2]=='D')){
if(a[r2][c2]=='D') // did mecho just find home??
return true; // success!
m[r2][c2] = m[r][c] + 1;
q2.emplace(r2, c2);
}
}
}
// the bees' possible locations "expand" by 1 second
while(!q.empty()){ // bfs
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(good(r2, c2)&&b[r2][c2]==-1&&(a[r2][c2]=='G'||a[r2][c2]=='M')){
b[r2][c2] = b[r][c] + 1;
q.emplace(r2, c2);
}
}
}
}
return false; // mecho never found home without encountering bees :(
}
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 >> a[i][j];
if(a[i][j]=='M')
st = {i, j};
else if(a[i][j]=='H')
h.emplace_back(i, j);
}
// binary search (yes this binary search might not be commonly seen, but it's shorter to write)
int ans = -1;
for(int u = int(1e6); u > 0; u /= 2)
while(ans + u <= int(1e6) && ok(ans + u))
ans += u;
cout << ans;
}
