#include <bits/stdc++.h>
#define DIM 810
using namespace std;
char s[DIM];
int a[DIM][DIM],b[DIM][DIM],dist[DIM][DIM],f[DIM*DIM];
deque <pair<int,int> > c,aux,d;
int di[] = {-1,1,0,0};
int dj[] = {0,0,-1,1};
int n,nr,i,j,xstart,ystart,xfin,yfin;
inline int inmat (int i, int j){
if (i >= 1 && j >= 1 && i <= n && j <= n)
return 1;
return 0;
}
int verif (int val){
/// mai intai vad cat se extind albinele dupa val secunde
c.clear();
memset (f,0,sizeof f);
for (i=1;i<=n;i++)
for (j=1;j<=n;j++){
b[i][j] = a[i][j];
if (a[i][j] == 1)
c.push_back(make_pair(i,j));
}
for (i=1;i<=val;i++){
aux.clear();
for (auto it : c){
int ic = it.first, jc = it.second;
for (int dir=0;dir<=3;dir++){
int iv = ic + di[dir];
int jv = jc + dj[dir];
if (inmat (iv,jv) && b[iv][jv] == 0){
aux.push_back(make_pair(iv,jv));
b[iv][jv] = 1;
}}}
c = aux;
f[i] = 1;
}
if (b[xstart][ystart])
return 0;
/// d - lista cu toate locurile in care pot sa ajung pana la secunda asta
memset (dist,0,sizeof dist);
d.clear();
d.push_back(make_pair(xstart,ystart));
dist[xstart][ystart] = 1;
while (!d.empty()){
int ic = d.front().first;
int jc = d.front().second;
d.pop_front();
if (dist[ic][jc] % nr == 0 && !f[dist[ic][jc] / nr + val]){
/// inseamna ca a mai trecut un minut si trb sa avansez cu albinele
f[dist[ic][jc] / nr + val] = 1;
aux.clear();
for (auto it : c){
int i = it.first, j = it.second;
for (int dir=0;dir<=3;dir++){
int iv = i + di[dir];
int jv = j + dj[dir];
if (inmat(iv,jv) && b[iv][jv] == 0){
aux.push_back(make_pair(iv,jv));
b[iv][jv] = 1;
}}}
c = aux;
}
for (int dir=0;dir<=3;dir++){
int iv = ic + di[dir];
int jv = jc + dj[dir];
if (inmat (iv,jv) && (b[iv][jv] == 0 || b[iv][jv] == 3) && !dist[iv][jv]){
if (iv == xfin && jv == yfin) /// am reusit sa ajung
return 1;
dist[iv][jv] = 1 + dist[ic][jc];
d.push_back(make_pair(iv,jv));
}}}
return 0;
}
int main (){
//ifstream cin ("date.in");
//ofstream cout ("date.out");
cin>>n>>nr;
for (i=1;i<=n;i++){
cin>>s+1;
for (j=1;j<=n;j++){
if (s[j] == 'T')
a[i][j] = 2;
if (s[j] == 'M'){
xstart = i, ystart = j;
//a[i][j] = 4;
}
if (s[j] == 'D'){
xfin = i, yfin = j;
a[i][j] = 3;
}
if (s[j] == 'H')
a[i][j] = 1;
}
}
/*for (i=1;i<=n;i++,cout<<endl)
for (j=1;j<=n;j++)
cout<<a[i][j]<<" ";
*/
int st = 0, dr = n*n, sol = -1;
while (st <= dr){
int mid = (st+dr)>>1;
if (verif (mid)){
sol = mid;
st = mid+1;
} else dr = mid-1;
}
cout<<sol;
return 0;
}
