#include <iostream>
#include <cstdio>
#include <vector>
#include <cmath>
#include <queue>
using namespace std;
vector<vector<char>> grd(802, vector<char>(802, 'T'));
vector<vector<bool>> swm(802, vector<bool>(802, false));
vector<vector<int>> btime(802, vector<int>(802, 1e8));
int sttr, sttc;
int dstr, dstc;
int h, s;
vector<int> radd = { -1, 0, 1, 0 };
vector<int> cadd = { 0, -1, 0, 1 };
bool check(int tchk)
{
queue<pair<int, pair<int, int>>> bfs;
bfs.push({ 0, {sttr, sttc} });
vector<vector<bool>> poss(h + 2, vector<bool>(h + 2, false));
poss[sttr][sttc] = true;
while (!bfs.empty() && !poss[dstr][dstc])
{
int r = bfs.front().second.first, c = bfs.front().second.second, dst = bfs.front().first;
bfs.pop();
for (int dir = 0; dir < 4; dir++) if (!poss[r + radd[dir]][c + cadd[dir]]) if (grd[r + radd[dir]][c + cadd[dir]] == 'G')
if ((dst + 1) / s < btime[r + radd[dir]][c + cadd[dir]] - tchk)
{
poss[r + radd[dir]][c + cadd[dir]] = true;
bfs.push({ dst + 1, {r + radd[dir], c + cadd[dir]} });
}
}
return poss[dstr][dstc];
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> h >> s;
queue<pair<int, int>> swmpcs;
for (int i = 1; i <= h; i++) for (int j = 1; j <= h; j++)
{
cin >> grd[i][j];
if (grd[i][j] == 'M')
{
sttr = i;
sttc = j;
grd[i][j] = 'G';
}
else if (grd[i][j] == 'D')
{
dstr = i;
dstc = j;
grd[i][j] = 'T';
}
else if (grd[i][j] == 'H')
{
swmpcs.push({ i, j });
swm[i][j] = true;
grd[i][j] = 'T';
}
}
while (!swmpcs.empty())
{
int r = swmpcs.front().first, c = swmpcs.front().second;
swmpcs.pop();
for (int dir = 0; dir < 4; dir++) if ((!swm[r + radd[dir]][c + cadd[dir]]) && (grd[r + radd[dir]][c + cadd[dir]] == 'G'))
{
swm[r + radd[dir]][c + cadd[dir]] = true;
btime[r + radd[dir]][c + cadd[dir]] = btime[r][c] + 1;
swmpcs.push({ r + radd[dir], c + cadd[dir] });
}
}
btime[dstr][dstc] = btime[sttr][sttc];
grd[dstr][dstc] = 'G';
if (!check(0)) cout << -1;
else
{
int l = 0, r = btime[sttr][sttc] - 1;
while (l < r)
{
int mid = l + (r - l + 1) / 2;
if (check(mid)) l = mid;
else r = mid - 1;
}
cout << l;
}
}
