#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
const int dx[4] = {0, 1, 0, -1};
const int dy[4] = {1, 0, -1, 0};
int n, sx, sy, fx, fy, dB[810][810], d[810][810], S;
char a[810][810];
bool f(int bound){
for (int i = 1; i <= n; i++){
for (int j = 1; j <= n; j++)
d[i][j] = 1e9;
}
d[sx][sy] = 0;
queue <pair<int, int> > q;
q.push({sx, sy});
while(!q.empty()){
int x = q.front().first, y = q.front().second;
q.pop();
int curTime = bound + max(0, (d[x][y]))/S;
if (curTime >= dB[x][y])
continue;
for (int i = 0; i < 4; i++){
int xx = x + dx[i], yy = y + dy[i];
if (xx < 1 || yy < 1 || xx > n || yy > n || a[xx][yy] == 'T' || curTime >= dB[xx][yy])
continue;
if (d[x][y] + 1 < d[xx][yy]){
d[xx][yy] = d[x][y] + 1;
q.push({xx, yy});
}
}
}
return d[fx][fy] != 1e9;
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n >> S;
queue <pair<int, int> > q;
for (int i = 1; i <= n; i++){
for (int j = 1; j <= n; j++){
cin >> a[i][j];
dB[i][j] = 1e9;
if (a[i][j] == 'H'){
q.push({i, j});
dB[i][j] = 0;
}
if (a[i][j] == 'M'){
sx = i; sy = j;
}
if (a[i][j] == 'D'){
fx = i; fy = j;
}
}
}
while(!q.empty()){
int x = q.front().first, y = q.front().second;
q.pop();
for (int i = 0; i < 4; i++){
int xx = x + dx[i], yy = y + dy[i];
if (xx < 1 || yy < 1 || xx > n || yy > n || a[xx][yy] == 'T' || a[xx][yy] == 'D')
continue;
if (dB[x][y] + 1 < dB[xx][yy]){
dB[xx][yy] = dB[x][y] + 1;
q.push({xx, yy});
}
}
}
int l = 0, r = 2000000;
while(l < r){
int mid = (l+r+1)>>1;
if (f(mid))
l = mid; else
r = mid-1;
}
if (f(l) == 0)
l = -1;
cout << l;
}
/**
4 3
TTDT
THGT
TTGT
TTGM
*/
