#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long int ll;
typedef vector<ll> vi;
typedef vector<vector<ll>> vvi;
typedef pair<ll,ll> pi;
typedef map<ll,ll> mi;
typedef long double ld;
typedef vector<ld> vd;
typedef vector<vector<ld>> vvd;
typedef pair<ld,ld> pd;
#define ff first
#define ss second
#define srt(a) sort(a.begin(),a.end());
#define fip(k, n) for (ll i = k; i < n; i++)
#define fjp(k, n) for (ll j = k; j < n; j++)
#define fin(k, n) for (ll i = k; i >= n; i--)
#define fjn(k, n) for (ll j = k; j >= n; j--)
#define fp(k, n, m) for (ll k = n; k < m; k++)
#define fn(k, n, m) for (ll k = n; k >= m; k--)
#define ordered_set tree<pi, null_type,less< pi >, rb_tree_tag,tree_order_statistics_node_update>
#define totalOne(n) __builtin_popcount(n)
#define backZero(n) __builtin_ctzll(n)
#define frontZero(n) __builtin_clzll(n)
#define fx(k) for ( auto x : k )
#define test ll t;cin >> t;while (t--)
#define nli "\n"
// ==========================(debug)============================================================================================== //
#ifndef ONLINE_JUDGE
#define debug(x) cerr << #x <<" "; _printn(x); cerr << nli;
#else
#define debug(x)
#endif
void _printn(ll x){ cerr<<x<<" "; }
void _printn(int x){ cerr<<x<<" "; }
void _printn(ld x){ cerr<<x<<" "; }
void _printn(double x){ cerr<<x<<" "; }
void _printn(string x){ cerr<<x<<" "; }
void _printn(char x){ cerr<<x<<" "; }
void _printn(bool x){ cerr<<x<<" "; }
template<class T,class V>void _printn(pair<T,V> vv);
template<class T> void _printn(vector<T> vv);
template<class T> void _printn(set<T> vv);
template<class T,class V> void _printn(map<T,V> vv);
template<class T> void _printn(multiset<T> vv);
template<class T,class V>void _printn(pair<T,V> vv){ cerr<<"( ";_printn(vv.ff);cerr<<",";_printn(vv.ss);cerr<<")";}
template<class T> void _printn(vector<T> vv){ cerr<<"[ "; for(auto xx:vv){ _printn(xx);cerr<<" "; } cerr<<"]"; };
template<class T> void _printn(set<T> vv){ cerr<<"{ "; for(auto xx:vv){ _printn(xx);cerr<<" "; } cerr<<"}"; };
template<class T> void _printn(multiset<T> vv){ cerr<<"{ "; for(auto xx:vv){ _printn(xx);cerr<<" "; } cerr<<"}"; };
template<class T,class V> void _printn(map<T,V> vv){ cerr<<"{ "; for(auto xx:vv){ _printn(xx);cerr<<" "; } cerr<<"}"; };
// ==========================(debug)============================================================================================== //
ll n,m,tp,tp2,res,cnt,sum,tptp,ans;
const ll mx = 800+5;
const ll mod = 1e9+7;
// ==========================(MOD)=============================================================================================== //
ll mod_add(ll aa,ll bb){ return ((aa%mod)+(bb%mod))%mod; }
ll mod_minus(ll aa,ll bb){ return (((aa%mod)-(bb%mod))+10*mod)%mod; }
ll mod_mul(ll aa,ll bb){ return ((aa%mod)*(bb%mod))%mod; }
ll mod_power(ll aa,ll bb){ aa%=mod; ll empowered = 1; bb%=mod-1; while(bb > 0){ if(bb & 1) empowered = mod_mul(empowered,aa); bb = bb >> 1; aa = mod_mul(aa,aa); } return empowered; }
ll mod_divi(ll aa,ll bb){ aa=mod_mul(aa,mod_power(bb,mod-2)); return aa; }
// ==========================(MOD)=============================================================================================== //
bool f = false;
char c[mx][mx];
queue<pi> q;
ll dx[4] = {1,0,-1,0};
ll dy[4] = {0,1,0,-1};
pi pos,house;
vector<pi> v;
ll vis[mx][mx];
ll vis2[mx][mx];
bool ok(ll x,ll y){
return (x >= 0 && x < n && y >= 0 && y < n && vis[x][y] == -1 && (c[x][y] == 'M' || c[x][y] == 'G'));
}
bool ok2(ll x,ll y){
return (x >= 0 && x < n && y >= 0 && y < n && vis2[x][y] == -1 && (c[x][y] == 'M' || c[x][y] == 'G'));
}
void emptify(){
while(q.size())
q.pop();
return;
}
bool meow(ll k){
fip(0,n+2)
fjp(0,n+2){
vis2[i][j] = -1;
vis[i][j] = -1;
}
emptify();
fx(v){
vis[x.ff][x.ss] = 0;
q.push({x.ff,x.ss});
}
while(q.size()){
pi x = q.front();
// debug(x);
q.pop();
fip(0,4){
if(ok(x.ff+dx[i],x.ss+dy[i])){
vis[x.ff+dx[i]][x.ss+dy[i]] = vis[x.ff][x.ss] + 1;
q.push({x.ff+dx[i],x.ss+dy[i]});
}
}
}
emptify();
q.push(pos);
vis2[pos.ff][pos.ss] = 0;
if(vis[pos.ff][pos.ss] <= k)
q.pop();
while(q.size()){
auto x = q.front();
q.pop();
fip(0,4)
if(ok2(x.ff+dx[i],x.ss+dy[i])){
if(((vis2[x.ff][x.ss] + 1) / m) + k >= vis[x.ff+dx[i]][x.ss+dy[i]])
continue;
vis2[x.ff+dx[i]][x.ss+dy[i]] = (vis2[x.ff][x.ss] + 1) ;
q.push({x.ff+dx[i],x.ss+dy[i]});
}
}
// fip(0,n){
// fjp(0,n){
// cout<<vis[i][j];
// }
// cout<<nli;
// }
fip(0,n)
fjp(0,n){
if(-1 != vis2[i][j])
vis2[i][j]/=m;
}
// fip(0,n){
// fjp(0,n){
// cout<<vis2[i][j];
// }
// cout<<nli;
// }
f = 0;
fip(0,4)
if(house.ff + dx[i] >= 0 && house.ff + dx[i] < n && house.ss + dy[i] >= 0 && house.ss + dy[i] < n && c[house.ff+dx[i]][house.ss+dy[i]] != 'T'){
if(vis2[house.ff+dx[i]][house.ss+dy[i]] != -1 && vis2[house.ff + dx[i]][house.ss + dy[i]] + k < vis[house.ff + dx[i]][house.ss + dy[i]]){
f = 1;
}
}
return f;
}
ll l,r,mid;
int main(){
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
// #ifndef ONLINE_JUDGE
// freopen("input1.txt", "r", stdin);
// freopen("output1.txt", "w", stdout);
// freopen("error1.txt", "w", stderr);
// #endif // ONLINE_JUDGE
cin>>n>>m;
ans = -1;
fip(0,n)
fjp(0,n){
cin>>c[i][j];
if(c[i][j]=='H')
v.push_back({i,j});
else if(c[i][j]=='M')
pos = {i,j};
else if(c[i][j]=='D')
house = {i,j};
}
// cout<<meow(3)<<nli;
l = 0,r = 1e9;
while(l<=r){
mid = l + (r-l)/2;
if(meow(mid)){
ans = mid;
l = mid + 1;
}else
r = mid - 1;
}
cout<<ans<<nli;
cerr << "Time elapsed: " << setprecision(6) << 1000.0 * clock() / CLOCKS_PER_SEC << "ms\n";
return 0;
}
