#include<iostream>
#include<vector>
#include<queue>
#include<string>
#include<fstream>
#include<algorithm>
#define For(i, n) for(int i = 0; i < n; i++)
#define ffor(i, a, n) for(int i = a; i < n; i++)
#define vec vector
#define ff first
#define ss second
#define pb push_back
#define pairs pair<int, int>
#define NEK 1000000000
using namespace std;
vec<pairs> r = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
void BFS(queue<pairs>&q, vec<vec<char>>&p, vec<vec<int>>&d) {
while (!q.empty()) {
pairs x = q.front(); q.pop();
For(i, 4) {
pairs t = { x.ff + r[i].ff, x.ss + r[i].ss };
if (t.ff < 0 || t.ss < 0 || t.ff >= p.size() || t.ss >= p.size()) continue;
if (p[t.ff][t.ss] == 'T' || p[t.ff][t.ss] == 'D') continue;
if (d[t.ff][t.ss] != -1) continue;
d[t.ff][t.ss] = d[x.ff][x.ss] + 1;
q.push(t);
}
}
}
bool BFS2(queue<pairs> q, vec<vec<char>>& p, vec<vec<int>>& d, int& s, pairs& e, int& c) {
vec<vec<int>> d2(p.size(), vec<int>(p.size(), -1));
d2[q.front().ff][q.front().ss] = 0;
if (d2[q.front().ff][q.front().ss] >= (d[q.front().ff][q.front().ss] - c)) return false;
while (!q.empty()) {
pairs x = q.front(); q.pop();
if (x.ff == e.ff && x.ss == e.ss) return true;
For(i, 4) {
pairs t = { x.ff + r[i].ff, x.ss + r[i].ss };
if (t.ff < 0 || t.ss < 0 || t.ff >= p.size() || t.ss >= p.size()) {
continue;
}
if (p[t.ff][t.ss] == 'T' || d2[t.ff][t.ss] != -1) continue;
d2[t.ff][t.ss] = d2[x.ff][x.ss] + 1;
if ((d2[t.ff][t.ss] / s) >= (d[t.ff][t.ss] - c) && d[t.ff][t.ss] != -1) continue;
q.push(t);
}
}
return false;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
//ifstream cin("atlarge.in");
//ofstream cout("atlarge.out");
int n, v;
cin >> n >> v;
vec<vec<char>> p(n, vec<char>(n));
pairs s, e;
queue<pairs> q;
vec<vec<int>> d1(n, vec<int>(n, -1));
For(i, n) {
For(j, n) {
cin >> p[i][j];
if (p[i][j] == 'M') {
s = { i, j };
}
if (p[i][j] == 'D') {
e = { i, j };
}
if (p[i][j] == 'H') {
q.push({ i, j });
d1[i][j] = 0;
}
}
}
BFS(q, p, d1);
int l = 0, r = n*n;
q.push(s);
while (l < r) {
int c = (l + r) / 2 + 1;
if (BFS2(q, p, d1, v, e, c)) l = c;
else r = c-1;
}
if (BFS2(q, p, d1, v, e, l)) cout << l << '\n';
else cout << -1 << '\n';
return 0;
}
