#include <bits/stdc++.h>
#define vi vector<int>
#define ve vector
#define ll long long
#define vl vector<ll>
#define vll vector<pair<ll,ll>>
#define onbit __builtin_popcount
#define ii pair<int,int>
#define vvi vector<vi>
#define vii vector<ii>
#define gii greater<ii>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define INF 1e18
#define eps 1e-7
#define eps1 1e-2
#define optimise ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define MAX_A 1e5+5
using namespace std;
const int MOD = 1e9+7;
const int nax = 805;
const int MAX_VAL = 1e6;
double PI=3.14159265359;
int arx[8]={1,1,0,-1,-1,-1, 0, 1};
int ary[8]={0,1,1, 1, 0,-1,-1,-1};
typedef complex<int> Point;
#define X real()
#define Y imag()
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
char tab[nax][nax];
int dis[nax][nax];
int n,k;
bool test;
int vis[nax][nax];
pair<int,int> last;
bool inside(int x,int y)
{
return (x>=0&&x<n&&y>=0&&y<n&&tab[x][y]!='T'&&tab[x][y]!='D');
}
bool mecho(int x,int y)
{
return (x>=0&&x<n&&y>=0&&y<n&&tab[x][y]!='T'&&tab[x][y]!='H');
}
void dfs(int sum)
{
queue<pair<pair<int,int>,int>> dq;
dq.push({{last.fi,last.se},0});
vis[last.fi][last.se]=sum;
while(!dq.empty())
{
int x=dq.front().fi.fi;
int y=dq.front().fi.se;
int z=dq.front().se;
dq.pop();
for(int i=0;i<7;i+=2)
{
int a=x+arx[i];
int b=y+ary[i];
int c=0;
c+= (z==k);
int p=z;
if (p==k) p=0;
if (!mecho(a,b)) continue;
if (vis[a][b]!=-1) continue;
if (dis[a][b]<=c+vis[x][y]&&dis[a][b]!=-1) continue;
if (tab[a][b]=='D'){
/*cout << "nabba"<<endl;
for (int i = 0; i < n; ++i)
{
for (int j = 0; j < n; ++j)
{
cout << vis[i][j]<<" ";
}cout<< endl;
}*/
test=true;
return;
}
vis[a][b]=vis[x][y]+c;
dq.push({{a,b},p+1});
}
}
/*for (int i = 0; i < n; ++i)
{
for (int j = 0; j < n; ++j)
{
cout << vis[i][j]<<" ";
}cout<< endl;
}*/
}
int main(){
optimise;
/*#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif*/
//setIO("atlarge");
cin>>n>>k;
memset(dis,-1,sizeof dis);
queue<pair<int,int>> q;
for (int i = 0; i < n; ++i)
{
for (int j = 0; j < n; ++j)
{
cin>>tab[i][j];
if (tab[i][j]=='H'){
q.push({i,j});
dis[i][j]=0;
}
if (tab[i][j]=='M'){
last.fi=i;
last.se=j;
}
}
}
while(!q.empty())
{
int x=q.front().fi;
int y=q.front().se;
q.pop();
for(int i=0;i<7;i+=2)
{
int a=x+arx[i];
int b=y+ary[i];
if (!inside(a,b)) continue;
if (dis[a][b]!=-1) continue;
dis[a][b]=dis[x][y]+1;
q.push({a,b});
}
}
/*for (int i = 0; i < n; ++i)
{
for (int j = 0; j < n; ++j)
{
cout << dis[i][j]<<" ";
}cout << endl;
}*/
int l=0;
int r=1e6;
while(r-l>1){
int mid=(r+l)/2;
//if (mid<10) cout << mid<<endl;
memset(vis,-1,sizeof vis);
test=false;
dfs(mid);
if(test) l=mid;
else r=mid;
}
if (l<=0){
cout <<-1<<endl;
}else cout << l<<endl;
}
