#include <bits/stdc++.h>
using namespace std;
#define int long long
#define forinc(i,a,b) for(int i=a;i<=b;++i)
#define fordec(i,a,b) for(int i=a;i>=b;--i)
#define pb push_back
#define eb emplace_back
#define pii pair <int,int>
#define fi first
#define se second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
const int N = 888, inf = 1e15;
const int H[] = {1, 0, -1, 0};
const int C[] = {0, 1, 0, -1};
int n, s, cti = inf;
char a[N][N];
int t[N][N], f[N][N], m[N][N];
pii sta, fin;
bool valid (const int& x, const int& y)
{
return x && y && x <= n && y <= n
&& a[x][y] != 'T';
}
bool ok (const int& tg)
{
queue <pii> q; q.push(sta);
forinc(i,1,n) forinc(j,1,n) f[i][j] = inf;
if(tg >= t[sta.fi][sta.se]) return 0;
f[sta.fi][sta.se] = tg;
while(q.size()) {
auto x = q.front(); q.pop();
if(x == fin) return 1;
forinc(i,0,3) {
int nh = x.fi + H[i];
int nc = x.se + C[i];
if(valid(nh, nc) && f[nh][nc] > f[x.fi][x.se] + 1) {
f[nh][nc] = f[x.fi][x.se] + 1;
m[nh][nc] = (m[x.fi][x.se] + 1) % s;
int diff = f[nh][nc] - tg - 1;
diff /= s;
diff += tg + 1;
if(diff < t[nh][nc] || (diff == t[nh][nc] && m[nh][nc]))
q.push({nh, nc});
}
}
}
return 0;
}
void solve ()
{
queue <pii> q;
forinc(i,1,n) forinc(j,1,n) {
t[i][j] = inf;
if(a[i][j] == 'H') {
q.push({i, j});
t[i][j] = 0;
}
else if(a[i][j] == 'M') sta = {i, j};
else if(a[i][j] == 'D') fin = {i, j};
}
// bfs bee
while(q.size()) {
auto x = q.front(); q.pop();
forinc(i,0,3) {
int nh = x.fi + H[i];
int nc = x.se + C[i];
if(valid(nh, nc) && a[nh][nc] != 'D' && t[nh][nc] > t[x.fi][x.se] + 1) {
t[nh][nc] = t[x.fi][x.se] + 1;
q.push({nh, nc});
}
}
}
// binary search
int l = 0, r = n * n, ans = -1;
while(l <= r) {
int mid = l + r >> 1;
if(ok(mid)) {
ans = mid;
l = mid + 1;
}
else r = mid - 1;
}
cout << ans;
}
void read ()
{
cin >> n >> s;
forinc(i,1,n) forinc(j,1,n)
cin >> a[i][j];
solve();
}
main ()
{
#define task "ioi09_mecho"
cin.tie(0) -> sync_with_stdio(0);
if(fopen (task ".inp", "r")) {
freopen (task ".inp", "r", stdin);
freopen (task ".out", "w", stdout);
}
read();
return 0;
}
