#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ff first
#define ss second
#define pb push_back
#define mk make_pair
#define IOS ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n,m;
int b[805][806];
queue<pair<int,int> > q;
int stx, sty;
int cnt[805][805];
int tmp[805][805];
bool check = 0;
char ch[805][805];
int main() {
IOS
cin >> n >> m;
for(int i = 1; i <= n; i ++) {
for(int j = 1; j <= n; j ++) {
cin >> ch[i][j];
if(ch[i][j] == 'H') {
b[i][j] = 1;
q.push({i,j});
}
if(ch[i][j] == 'M') {
stx = i;
sty = j;
}
}
}
while(q.size() > 0) {
int x = q.front().ff;
int y = q.front().ss;
q.pop();
if(x > 1 && b[x - 1][y] == 0 && ch[x - 1][y] != 'T' && ch[x - 1][y] != 'D') {
q.push({x - 1, y});
b[x - 1][y] = b[x][y] + 1;
}
if(x < n && b[x + 1][y] == 0 && ch[x + 1][y] != 'T' && ch[x + 1][y] != 'D') {
q.push({x + 1, y});
b[x + 1][y] = b[x][y] + 1;
}
if(y > 1 && b[x][y - 1] == 0 && ch[x][y - 1] != 'T' && ch[x][y - 1] != 'D') {
q.push({x, y - 1});
b[x][y - 1] = b[x][y] + 1;
}
if(y < n && b[x][y + 1] == 0 && ch[x][y + 1] != 'T' && ch[x][y + 1] != 'D') {
q.push({x, y + 1});
b[x][y + 1] = b[x][y] + 1;
}
}
for(int i = 1; i <= n; i ++) {
for(int j = 1; j <= n; j ++) {
if(b[i][j] == 0) b[i][j] = 1e9;
}
}
int l = 0;
int r = n * n;
while(l < r) {
int mid = (l + r + 1) / 2;
memset(cnt, -1, sizeof(cnt));
while(q.size() > 0) q.pop();
q.push({stx,sty});
cnt[stx][sty] = mid;
tmp[stx][sty] = m;
bool ok = 0;
while(q.size() > 0) {
int x = q.front().ff;
int y = q.front().ss;
q.pop();
int num = cnt[x][y];
int move = tmp[x][y];
if(tmp[x][y] == m) {
num ++;
move = 0;
}
move ++;
//
if(x > 1 && cnt[x - 1][y] == -1 && num < b[x - 1][y] && ch[x - 1][y] != 'T') {
if(ch[x - 1][y] == 'D') { // home location
ok = 1; break;
}
cnt[x - 1][y] = num;
tmp[x - 1][y] = move;
q.push({x - 1, y});
}
//
if(x < n && cnt[x + 1][y] == -1 && num < b[x + 1][y] && ch[x + 1][y] != 'T') {
if(ch[x + 1][y] == 'D') { // home location
ok = 1; break;
}
cnt[x + 1][y] = num;
tmp[x + 1][y] = move;
q.push({x + 1, y});
}
//
if(y > 1 && cnt[x][y - 1] == -1 && num < b[x][y - 1] && ch[x][y - 1] != 'T') {
if(ch[x][y - 1] == 'D') { // home location
ok = 1; break;
}
cnt[x][y - 1] = num;
tmp[x][y - 1] = move;
q.push({x, y - 1});
}
//
if(y < n && cnt[x][y + 1] == -1 && num < b[x][y + 1] && ch[x][y + 1] != 'T') {
if(ch[x][y + 1] == 'D') { // home location
ok = 1; break;
}
cnt[x][y + 1] = num;
tmp[x][y + 1] = move;
q.push({x, y + 1});
}
}
if(ok == 1) {
check = 1;
l = mid;
}
else r = mid - 1;
}
if(check == 1){
cout << l + 1;
}
else cout << -1;
}
