#pragma GCC optimize("Ofast")
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define sz(a) (int)(a.size())
#define all(a) a.begin(),a.end()
#define lb lower_bound
#define ub upper_bound
#define owo ios_base::sync_with_stdio(0);cin.tie(0);
#define INF (ll)(1e18)
#define debug(...) fprintf(stderr, __VA_ARGS__),fflush(stderr)
#define time__(d) for(long blockTime = 0; (blockTime == 0 ? (blockTime=clock()) != 0 : false);\
debug("%s time : %.4fs\n", d, (double)(clock() - blockTime) / CLOCKS_PER_SEC))
typedef long long int ll;
typedef long double ld;
typedef pair<ll,ll> PII;
typedef pair<int,int> pii;
typedef vector<vector<int>> vii;
typedef vector<vector<ll>> VII;
ll gcd(ll a,ll b){if(!b)return a;else return gcd(b,a%b);}
int n,s,dx[4] = {0,0,1,-1},dy[4] = {1,-1,0,0};
int dist[1000][1000],bdist[1000][1000],blk[1000][1000];
char grid[1000][1000];
pii st,ed;
bool check(int tim){
queue<pii>bee;
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
dist[i][j] = bdist[i][j] = 1e9;
blk[i][j] = 1;
if(grid[i][j] == 'H'){
bee.push({i,j});
bdist[i][j] = 0;
}
if(grid[i][j] != 'H' && grid[i][j] != 'T')blk[i][j] = 0;
}
}
while(!bee.empty()){
auto v = bee.front();
if(bdist[v.fi][v.se] == tim+1)break;
bee.pop();
blk[v.fi][v.se] = 1;
for(int i=0;i<4;i++){
int x = v.fi+dx[i];
int y = v.se+dy[i];
if(x>=0 && y>=0 && x<n && y<n && bdist[x][y] == 1e9 && grid[x][y] == 'G'){
bee.push({x,y});
bdist[x][y] = bdist[v.fi][v.se]+1;
}
}
}
queue<pii>q;
q.push(st);
dist[st.fi][st.se] = 0;
int cnt = 1;
while(!q.empty()){
pii v = q.front();
q.pop();
if((dist[v.fi][v.se]+s-1)/s > cnt){ //move the bees
cnt++;
tim++;
while(!bee.empty()){
auto v = bee.front();
if(bdist[v.fi][v.se] == tim+1)break;
bee.pop();
blk[v.fi][v.se] = 1;
for(int i=0;i<4;i++){
int x = v.fi+dx[i];
int y = v.se+dy[i];
if(x>=0 && y>=0 && x<n && y<n && bdist[x][y] == 1e9 && grid[x][y] == 'G'){
bee.push({x,y});
bdist[x][y] = bdist[v.fi][v.se]+1;
}
}
}
}
if(blk[v.fi][v.se])continue;
for(int i=0;i<4;i++){
int x = v.fi+dx[i];
int y = v.se+dy[i];
if(x>=0 && y>=0 && x<n && y<n && !blk[x][y] && dist[x][y] == 1e9){
q.push({x,y});
dist[x][y] = dist[v.fi][v.se]+1;
}
}
}
return dist[ed.fi][ed.se] != 1e9;
}
int main()
{
owo
cin>>n>>s;
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
cin>>grid[i][j];
if(grid[i][j] == 'M')st = {i,j};
if(grid[i][j] == 'D')ed = {i,j};
}
}
if(!check(0)){
cout<<-1;
return 0;
}
int l = 0,r = n*n;
while(r>=l){
int mid = (l+r)/2;
if(check(mid))l = mid+1;
else r = mid-1;
}
cout<<r<<'\n';
}
