#include <bits/stdc++.h>
using namespace std;
#define a first
#define b second
#define pb push_back
typedef long long llo;
#define endl '\n'
int n,s;
queue<pair<int,int>> ss;
int dist[801][801];
int it[801][801];
vector<int> x={1,-1,0,0};
vector<int> y={0,0,1,-1};
int dd[801][801];
pair<int,int> aa;
pair<int,int> bb;
bool check(int mid){
queue<pair<int,int>> tt;
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
dd[i][j]=-1;
}
}
dd[aa.a][aa.b]=0;
tt.push({aa.a,aa.b});
while(tt.size()){
pair<int,int> no=tt.front();
tt.pop();
//if(dd[no.a][no.b])
for(int i=0;i<4;i++){
int xx=no.a+x[i];
int yy=no.b+y[i];
if(xx<0 or xx>=n or yy<0 or yy>=n){
continue;
}
if(it[xx][yy]==0){
continue;
}
if(dd[xx][yy]==-1){
if(dist[xx][yy]!=-1){
if(dist[xx][yy]<=mid+(dd[no.a][no.b]+1)/s){
continue;
}
}
dd[xx][yy]=dd[no.a][no.b]+1;
//cout<<xx<<":"<<yy<<":"<<dd[xx][yy]<<endl;
tt.push({xx,yy});
}
}
}
/*for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
cout<<dd[i][j]<<",";
}
cout<<endl;
}
cout<<mid<<":"<<dd[bb.a][bb.b]<<endl;*/
return dd[bb.a][bb.b]!=-1;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin>>n>>s;
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
dist[i][j]=-1;
char s;
cin>>s;
it[i][j]=1;
if(s=='T'){
it[i][j]=0;
}
else if(s=='G'){
}
else if(s=='M'){
aa={i,j};
}
else if(s=='D'){
it[i][j]=0;
bb={i,j};
}
else if(s=='H'){
ss.push({i,j});
dist[i][j]=0;
}
}
}
while(ss.size()){
pair<int,int> no=ss.front();
ss.pop();
for(int i=0;i<4;i++){
int xx=no.a+x[i];
int yy=no.b+y[i];
if(xx<0 or xx>=n or yy<0 or yy>=n){
continue;
}
if(it[xx][yy]==0){
continue;
}
if(dist[xx][yy]==-1){
dist[xx][yy]=dist[no.a][no.b]+1;
ss.push({xx,yy});
}
}
}
int low=0;
int high=dist[aa.a][aa.b]-1;
it[bb.a][bb.b]=1;
if(check(low)==false){
cout<<-1<<endl;
}
else{
while(low<high-1){
int mid=(low+high)/2;
if(check(mid)){
low=mid;
}
else{
high=mid;
}
}
int ans=low;
if(check(high)){
ans=max(ans,high);
}
cout<<ans<<endl;
}
return 0;
}
