#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
// #pragma GCC target ("avx2")
// #pragma GCC optimize ("O3")
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC optimize("fast-math")
#define ll long long
#define ld long double
#define vi vector<ll>
#define endl "\n"
#define pr pair<ll, ll>
#define ff first
#define ss second
#define all(x) x.begin(), x.end()
const int mod = 1e9+7;
void _p(ll a){cout<<a<<endl;}
void _p(string a){cout<<a<<endl;}
void _p(ld a) {cout<<a<<endl;}
template <class T>
void _p(vector<T> a){for(T val:a)cout<<val<<" ";cout<<endl;}
#define debug(x) cout<<#x<<" -> ";_p(x)
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update > ordered_set;
vector<pr> move8 = {{1, 0}, {1, 1}, {0, 1}, {-1, 1}, {-1, 0}, {-1, -1}, {0, -1}, {1, -1}};
vector<pr> move4 = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
vector<pr> move2 = {{0, 1}, {1, 0}};
void solution();
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
solution();
return 0;
}
pr operator+(pr p1, pr p2) {
pr ans = {p1.ff +p2.ff, p1.ss+p2.ss};
return ans;
}
const int MAXN = 805;
char A[MAXN][MAXN];
ll n, s;
pr start, destination;
vector<pr> H;
bool vis1[MAXN][MAXN], vis2[MAXN][MAXN];
bool correct(pr cords) {
return cords.ff <= n && cords.ff >= 1 &&
cords.ss <= n && cords.ss >= 1 &&
A[cords.ff][cords.ss] != 'T';
}
bool isValid(ll T) {
set<pr> bad(all(H));
pr wa = {-1, -1};
queue<pr> q1, q2;
for (auto M : H) q2.push(M);
q2.push(wa);
ll k = 0;
while (!q2.empty()) {
pr e = q2.front(); q2.pop();
if (e == wa) {
if (q2.size() > 0) q2.push(wa);
if (k >= T) break;
k++;
continue;
}
if (vis2[e.ff][e.ss]) continue;
vis2[e.ff][e.ss] = true;
bad.insert(e);
for (auto D : move4) {
pr new_cords = e + D;
if (!correct(new_cords) || vis2[new_cords.ff][new_cords.ss]) continue;
q2.push(new_cords);
}
}
q1.push(start);
q1.push(wa);
k = 0;
while (!q1.empty()) {
pr e = q1.front(); q1.pop();
if (e == wa) {
// if time is up
if (k >= s) {
while (!q2.empty()) {
pr m = q2.front(); q2.pop();
if (m == wa) {
if (q2.size() > 0) q2.push(wa);
break;
}
if (vis2[m.ff][m.ss]) continue;
vis2[m.ff][m.ss] = true;
bad.insert(m);
for (auto D : move4) {
pr nkw = m + D;
if (!correct(nkw) || vis2[nkw.ff][nkw.ss]) continue;
q2.push(nkw);
}
}
k = 0;
}
k++;
if (q1.size() > 0) q1.push(wa);
}
if (bad.count(e) || vis1[e.ff][e.ss]) continue;
vis1[e.ff][e.ss] = true;
if (e == destination) return true;
for (auto D : move4) {
pr nkw = e + D;
if (!correct(nkw) || vis1[nkw.ff][nkw.ss]) continue;
q1.push(nkw);
}
}
return false;
}
void solution() {
cin >> n >> s;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
cin >> A[i][j];
if (A[i][j] == 'M') start = {i, j};
if (A[i][j] == 'D') destination = {i, j};
if (A[i][j] == 'H') H.push_back({i, j});
}
}
ll p = 0, q = 1e3;
ll ans = -1;
while (p <= q) {
ll mid = (p + q)/2;
if (isValid(mid)) {
ans = mid;
p = mid+1;
}else q = mid-1;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
vis1[i][j] = vis2[i][j] = 0;
}
}
}
cout << ans << endl;
}
