#include<bits/stdc++.h>
using namespace std;
const int maxn=810;
int marc[maxn][maxn], db[maxn][maxn], mb[maxn][maxn], dx[]={1,-1,0,0}, dy[]={0,0,1,-1}, dist[maxn][maxn], m[maxn][maxn], n;
bool in(int x, int y){
return 1<=x&&x<=n&&1<=y&&y<=n;
}
bool check(int tmp, int ix, int iy, int fx, int fy, int s){
queue<pair<int,int>>q;
q.push({ix,iy});
memset(dist,-1,sizeof(dist));
memset(m,0,sizeof(m));
dist[ix][iy]=tmp*s;
m[ix][iy]++;
if(db[ix][iy]<=tmp) return false;
while(!q.empty()){
int x=q.front().first, y=q.front().second, w=dist[x][y];
q.pop();
w++;
int at=w/s;
for(int i=0;i<4;i++){
int nx=x+dx[i], ny=y+dy[i];
if(in(nx,ny)&&!marc[nx][ny]&&!m[nx][ny]&&at<db[nx][ny]){
m[nx][ny]++;
dist[nx][ny]=w;
q.push({nx,ny});
}
}
}
return m[fx][fy];
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
int s; cin >> n >> s;
queue<pair<int,int>>bees;
int ix, iy, fx, fy;
for(int i=1;i<=n;i++)
for(int j=1;j<=n;j++){
db[i][j]=maxn*maxn;
char c; cin >> c;
if(c=='T') marc[i][j]=-1;
if(c=='H'){
bees.push({i,j});
mb[i][j]++;
db[i][j]=0;
}
if(c=='M'){
ix=i; iy=j;
}
if(c=='D'){
fx=i; fy=j;
}
}
while(!bees.empty()){
int x=bees.front().first, y=bees.front().second;
bees.pop();
for(int i=0;i<4;i++){
int nx=x+dx[i], ny=y+dy[i];
if(in(nx,ny)&&!mb[nx][ny]&&!marc[nx][ny]&&(nx!=fx||ny!=fy)){
db[nx][ny]=db[x][y]+1;
mb[nx][ny]++;
bees.push({nx,ny});
}
}
}
int l=0, r=maxn*maxn;
while(l<r){
int mid=(l+r+1)/2;
if(check(mid,ix,iy,fx,fy,s)) l=mid;
else r=mid-1;
}
if(!check(l,ix,iy,fx,fy,s)) cout << -1 << endl;
else cout << l << endl;
}
