// __builtin_popcount(x) broj bitova
// __builtin_popcountll(x) long long
#define here cerr<<"---------------------------\n"
#include "bits/stdc++.h"
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#define ld double
#define ll long long
#define ull unsigned long long
#define llinf 100000000000000000LL // 10^17
#define iinf 2000000000 // 2*10^9
#define pb push_back
#define popb pop_back
#define fi first
#define sc second
#define endl '\n'
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pld pair<ld,ld>
#define sz(a) int(a.size())
#define all(a) a.begin(),a.end()
#define rall(a) a.begin(),a.end(),greater<int>()
#define getunique(v) {sort(all(v)); v.erase(unique(all(v)), v.end());}
using namespace std;
using namespace __gnu_pbds;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
void setIO(string inoutname)
{
freopen((inoutname+".in").c_str(),"r",stdin);
freopen((inoutname+".out").c_str(),"w",stdout);
}
#define mod 1
ll gcd(ll a, ll b)
{
if(b==0) return a;
if(a==0) return b;
if(a>=b) return gcd(a%b,b);
return gcd(a,b%a);
}
ll lcm(ll a,ll b){
return (a/gcd(a,b))*b;
}
ll add(ll a,ll b){
a+=b;
a+=mod;
if(a>=mod) a%=mod;
return a;
}
ll mul(ll a,ll b){return(a*b)%mod;}
#define maxn 805
ll n,s;
ll a[maxn][maxn];
ll dm[maxn][maxn];
ll dh[maxn][maxn];
ll conv(char c){
if(c=='T') return 0;
if(c=='G') return 1;
if(c=='M') return 2;
if(c=='D') return 3;
if(c=='H') return 4;
}
vector<ll> dx = {0,0,-1,1};
vector<ll> dy = {1,-1,0,0};
vector<pll> hive;
ll sx,sy,ex,ey;
bool valid(ll x,ll y){return x>=1&&x<=n&&y>=1&&y<=n;}
bool moe(ll t){
if(t*s>=dh[sx][sy]) return 0;
for(ll i = 1;i<=n;i++) for(ll j = 1;j<=n;j++) dm[i][j] = llinf;
dm[sx][sy] = t*s;
queue<pll> q;
q.push({sx,sy});
while(!q.empty()){
pll p = q.front();
q.pop();
ll x = p.fi,y = p.sc;
if(a[x][y]==3) return 1;
for(ll i = 0;i<4;i++){
ll x1 = x + dx[i];
ll y1 = y + dy[i];
if(!valid(x1,y1)||dm[x1][y1]!=llinf||dh[x1][y1]<=dm[x][y]+1||a[x][y]==0) continue;
dm[x1][y1] = dm[x][y]+1;
q.push({x1,y1});
}
}
return 0;
}
ll bs(){
ll l = 0,r = n*n,mid,rez = -1;
while(l<=r){
mid = (l+r)/2;
if(moe(mid)){
rez = mid;
l = mid+1;
}else r = mid-1;
}
return rez;
}
void tc(){
ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);
cin >> n >> s;
for(ll i = 1;i<=n;i++){
string s1; cin >> s1;
for(ll j = 1;j<=n;j++){
a[i][j] = conv(s1[j-1]);
if(a[i][j]==2){
sx = i;
sy = j;
a[i][j] = 1;
}
if(a[i][j]==3){
ex = i;
ey = j;
}
if(a[i][j]==4){
hive.pb({i,j});
}
}
}
for(ll i = 1;i<=n;i++) for(ll j = 1;j<=n;j++) dh[i][j] = llinf;
queue<pll> q;
for(pll p : hive){
dh[p.fi][p.sc] = 0;
q.push(p);
}
while(!q.empty()){
pll p = q.front();
q.pop();
ll x = p.fi,y = p.sc;
for(ll i = 0;i<4;i++){
ll x1 = x + dx[i];
ll y1 = y + dy[i];
if(!valid(x1,y1)||a[x1][y1]!=1||dh[x1][y1]!=llinf) continue;
dh[x1][y1] = dh[x][y]+s;
q.push({x1,y1});
}
}
dh[ex][ey] = llinf;
cout<<bs()<<endl;
}
int main(){
ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);
//setIO("lol");
int t; t = 1;
while(t--){
tc();
}
return 0;
}
