#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
vector<vector<ll>> v;
ll N, S, ini, fin;
bool solve(ll T, deque<pair<ll, ll>> bfs, vector<bool> vis, vector<char> ori){
bfs.push_front({ini, -(T+1)});
vis[ini] = true;
while(bfs.size() != 0){
pair<ll, ll> p = bfs.front();
ll x = p.first;
ll e = p.second;
bfs.pop_front();
if(e == -1){
bfs.push_front({x, S+1});
continue;
}
if(e < -1){
bfs.push_back({x, e+1});
continue;
}
for(ll y : v[x]){
if(ori[x] == 'H'){ori[y] = 'H';}
if(vis[y]){continue;}
if(ori[y] == 'D' and ori[x] == 'H'){continue;}
vis[y] = true;
ori[y] = ori[x];
//cout<<"Casilla "<<y/N<<" "<<y%N<<" pasa a tener origen "<<ori[y]<<endl;
if(ori[x] == 'H'){
bfs.push_back({y, 0});
continue;
}
if(e == 1){bfs.push_back({y, S+1});}
if(e > 1){bfs.push_front({y, e-1});}
}
}
return (ori[fin] == 'M');
}
int main() {
cin.tie(nullptr);
ios_base::sync_with_stdio(false);
cin>>N>>S;
v.resize(N*N);
vector<char> c(N*N);
deque<pair<ll, ll>> d;
vector<bool> fij(N*N, false);
for(ll i=0;i<N;i++){
for(ll j=0;j<N;j++){
cin>>c[N*i+j];
if(c[N*i+j] == 'H'){
d.push_back({N*i+j, 0});
fij[N*i+j] = true;
}
if(c[N*i+j] == 'M'){ini = N*i+j;}
if(c[N*i+j] == 'D'){
fin = N*i+j;
}
}
}
for(ll i=0;i<N;i++){
for(ll j=0;j<N;j++){
if(i > 0 and c[N*(i-1)+j] != 'T'){
v[N*i+j].push_back(N*(i-1)+j);
}
if(i < N-1 and c[N*(i+1)+j] != 'T'){
v[N*i+j].push_back(N*(i+1)+j);
}
if(j > 0 and c[N*i+(j-1)] != 'T'){
v[N*i+j].push_back(N*i+(j-1));
}
if(j < N-1 and c[N*i+(j+1)] != 'T'){
v[N*i+j].push_back(N*i+(j+1));
}
}
}
solve(1, d, fij, c);
if(!(solve(0, d, fij, c))){cout<<-1; return 0;}
ll l = 0;
ll r = N*N;
while(r != l+1){
ll m = (l+r)/2;
if(solve(m, d, fij, c)){l = m;}
else{r = m;}
//cout<<l<<" "<<r<<endl;
}
cout<<l;
}
