#include <bits/stdc++.h>
#define all(dataStructure) dataStructure.begin(),dataStructure.end()
#define ll long long
using namespace std;
namespace std {
template <typename T, int D>
struct _vector : public vector <_vector <T, D - 1>> {
static_assert(D >= 1, "Dimension must be positive!");
template <typename... Args>
_vector(int n = 0, Args... args) : vector <_vector <T, D - 1>> (n, _vector <T, D - 1> (args...)) {}
};
// _vector <int, 3> a(n, m, k);: int a[n][m][k].
// _vector <int, 3> a(n, m, k, x);: int a[n][m][k] initialized with x.
template <typename T>
struct _vector <T, 1> : public vector <T> {
_vector(int n = 0, const T& val = T()) : vector <T> (n, val) {}
};
}
const int MAX = 8e2 + 3;
const ll MOD[] = {1000000007, 998244353};
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
char a[MAX][MAX];
int n, s;
int badTime[MAX][MAX];
bool vs[MAX][MAX];
int d[MAX][MAX];
bool ok(int i, int j) {
return i && j && max(i, j) <= n && a[i][j] != 'T';
}
void Solve() {
cin >> n >> s;
pair <int, int> house;
pair <int, int> start;
queue <pair <int, int>> q;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
cin >> a[i][j];
if (a[i][j] == 'D') house = {i, j};
if (a[i][j] == 'M') start = {i, j};
if (a[i][j] == 'H') {
vs[i][j] = 1;
q.push({i, j});
}
}
}
while (q.size()) {
auto [u, v] = q.front();
q.pop();
for (int i = 0; i < 4; i++) {
int x = u + dx[i];
int y = v + dy[i];
if (ok(x, y) && vs[x][y] == 0 && a[x][y] != 'D') {
vs[x][y] = 1;
badTime[x][y] = badTime[u][v] + 1;
q.push({x, y});
}
}
}
badTime[house.first][house.second] = 1e9;
auto check = [&](int val) -> bool {
memset(vs, 0, sizeof vs);
memset(d, 0, sizeof d);
vs[start.first][start.second] = 1;
queue <pair <int, int>> q;
q.push(start);
while (q.size()) {
if (q.front() == house) return 1;
auto [u, v] = q.front();
q.pop();
for (int i = 0; i < 4; i++) {
int x = u + dx[i];
int y = v + dy[i];
if (ok(x, y)) {
if (make_pair(x, y) == house) return 1;
if (vs[x][y] == 0 && (badTime[x][y] - (d[u][v] + 1) / s - 1) >= val) {
vs[x][y] = 1;
q.push({x, y});
d[x][y] = d[u][v] + 1;
}
}
}
}
return 0;
};
int ans = -1;
int l = 0, r = badTime[start.first][start.second];
while (l <= r) {
int mid = (l + r) / 2;
if (check(mid)) {
l = mid + 1;
ans = mid;
} else r = mid - 1;
}
cout << ans;
}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
#define TASK "TASK"
if (fopen(TASK".INP", "r")) {
freopen(TASK".INP", "r", stdin);
freopen(TASK".OUT", "w", stdout);
}
/* int TEST = 1; cin >> TEST; while (TEST--) */ Solve();
cerr << "\nTime elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << "s\n";
return 0;
}
