/*
*
* ^v^
*
*/
#include <iostream>
#include <string>
#include <cmath>
#include <vector>
#include <iomanip>
#include <map>
#include <numeric>
#include <functional>
#include <algorithm>
#include <set>
#include <queue>
#include <climits>
#include <cstdlib>
#include <chrono>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
using namespace std;
// #define ordered_set tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update>
#define iamtefu ios_base::sync_with_stdio(false); cin.tie(0);
#define ll long long int
#define ld long double
#define sc(a) scanf("%lld", &a);
#define scv(a, n) vector<ll> a(n);fl(i,0,n){sc(a[i])}
#define prl(a) fl(i,0,a.size()){printf("%lld ", a[i]);}printf("\n");
#define fl(i,a,n) for (ll i(a); i<n; i++)
#define rfl(i,a,n) for (ll i(n-1); i>=a; i--)
#define print(a) for (auto x:a){cout<<x<<" ";} cout<<"\n";
#define tt int tt; cin>>tt; for(;tt--;)
ll gcd(ll a, ll b){
if (b==0){
return a;
}
return gcd(b, a%b);
}
ll pw(ll a, ll b, ll m){
ll res=1;
a%=m;
while (b){
if (b&1){
res=(res*a)%m;
}
a=(a*a)%m;
b/=2;
}
return res;
}
void scn(){
ll n, s; cin>>n>>s;
vector <string> c(n);
vector <vector <ll>> a(n+1, vector <ll>(n+1, 1e9));
queue <vector <ll>> q;
fl(i,0,n){
cin>>c[i];
fl(j,0,n){
if (c[i][j]=='H'){
q.push({i, j});
a[i][j]=0;
}
}
}
vector <ll> di={1, 1, 0, -1, -1, -1, 0, 1};
vector <ll> dj={0, 1, 1, 1, 0, -1, -1, -1};
while (!q.empty()){
auto j = q.front();
q.pop();
for (int d=0; d<8; d+=2){
ll i1 = j[0]+di[d], j1 = j[1]+dj[d];
if (i1>=0 && j1>=0 && i1<n && j1<n && a[i1][j1]==1e9 && (c[i1][j1]=='G' || c[i1][j1]=='M')){
q.push({i1, j1});
a[i1][j1]=a[j[0]][j[1]]+1;
}
}
}
vector <vector <ll>> dis(n+1, vector <ll>(n+1, 1e9));
vector <ll> hij;
fl(i,0,n){
fl(j,0,n){
if (c[i][j]=='M'){
q.push({i, j});
dis[i][j]=0;
hij={i, j};
}
}
}
while (!q.empty()){
auto j = q.front();
q.pop();
for (int d=0; d<8; d+=2){
ll i1 = j[0]+di[d], j1 = j[1]+dj[d];
if (i1>=0 && j1>=0 && i1<n && j1<n && dis[i1][j1]==1e9 && (c[i1][j1]=='G' || c[i1][j1]=='D')){
dis[i1][j1]=dis[j[0]][j[1]]+1;
q.push({i1, j1});
}
}
}
for (auto &y:dis){
for (auto &x:y){
if (x!=1e9){
x=(x+s-1)/s;
}
}
}
if (a[hij[0]][hij[1]]==0){
cout<<"-1\n";
return;
}
// for (auto x:dis){
// print(x)
// }
// cout<<'\n';
// for (auto x:a){
// print(x)
// }
auto ist=[&](ll mid){
vector <vector <ll>> vis(n+1, vector <ll>(n+1));
queue <vector <ll>> q;
q.push({hij[0], hij[1], s});
vis[hij[0]][hij[1]]++;
while (!q.empty()){
auto j = q.front();
q.pop();
if (c[j[0]][j[1]]=='D'){
return true;
}
if (j[2]==0 && dis[j[0]][j[1]]+mid>=a[j[0]][j[1]]){
// cout<<dis[j[0]][j[1]]<<" "<<mid<<" "<<a[j[0]][j[1]]<<" pl1\n";
continue;
} else if (j[2] && dis[j[0]][j[1]]+mid-1>=a[j[0]][j[1]]){
continue;
}
// cout<<c[j[0]][j[1]]<<" pl\n";
for (int d=0; d<8; d+=2){
ll i1 = j[0]+di[d], j1 = j[1]+dj[d];
if (i1>=0 && i1<n && j1>=0 && j1<n && (c[i1][j1]=='D' || c[i1][j1]=='G') && vis[i1][j1]==0){
q.push({i1, j1, (j[2]==0?s-1:j[2]-1)});
vis[i1][j1]++;
}
}
}
return false;
};
ll l = 0, r = 1e18;
// cout<<ist(3)<<" o\n";
while (l<=r){
// cout<<l<<" "<<r<<'\n';
ll mid = (l+r)/2;
// cout<<mid<<" "<<ist(mid)<<" pl\n";
if (ist(mid)){
l = mid+1;
} else {
r = mid-1;
}
}
if (ist(0)==0){
cout<<"-1\n";
return;
}
cout<<max(0ll,l-1)<<'\n';
// not necessarily distinct
}
int main(){
iamtefu;
#if defined(airths)
auto t1=chrono::high_resolution_clock::now();
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#else
//
#endif
// tt
{
scn();
}
#if defined(airths)
auto t2=chrono::high_resolution_clock::now();
ld ti=chrono::duration_cast<chrono::nanoseconds>(t2-t1).count();
ti*=1e-6;
cerr<<"Time: "<<setprecision(12)<<ti;
cerr<<"ms\n";
#endif
return 0;
}
