#include <bits/stdc++.h>
#define int long long
using namespace std;
const int MAX_N = 4e5 + 5;
const int MOD = 998244353;
void solve() {
int n, s;
cin >> n >> s;
string grid[n];
int sx=0, sy=0;
vector<vector<int>>depth(n, vector<int>(n, -1));
queue<pair<int,int>>q;
for(int i=0; i<n; ++i) {
cin >> grid[i];
for(int j=0; j<n; ++j) {
if(grid[i][j] == 'M') {
sx=i;
sy=j;
}
else if(grid[i][j] == 'H') {
q.push({i, j});
depth[i][j] = 0;
}
}
}
while(!q.empty()) {
int x = q.front().first, y = q.front().second;
q.pop();
if(x && grid[x-1][y] != 'T' && depth[x-1][y] == -1) {
depth[x-1][y] = depth[x][y] + 1;
q.push({x-1, y});
}
if(y && grid[x][y-1] != 'T' && depth[x][y-1] == -1) {
depth[x][y-1] = depth[x][y] + 1;
q.push({x, y-1});
}
if(x+1<n && grid[x+1][y] != 'T' && depth[x+1][y] == -1) {
depth[x+1][y] = depth[x][y] + 1;
q.push({x+1, y});
}
if(y+1<n && grid[x][y+1] != 'T' && depth[x][y+1] == -1) {
depth[x][y+1] = depth[x][y] + 1;
q.push({x, y+1});
}
}
priority_queue<pair<pair<int,int>, pair<int,int>>>pq;
pq.push({{depth[sx][sy], 0}, {sx, sy}});
while(!pq.empty()) {
int t = pq.top().first.first, visited = pq.top().first.second, x = pq.top().second.first, y = pq.top().second.second;
pq.pop();
if(grid[x][y] == 'D') {
cout << t << endl;
return;
}
int new_t, cost = (visited+1)/s + ((visited+1) % s > 0 ? 1 : 0);
if(x && grid[x-1][y] != 'T') {
new_t = min(t, depth[x-1][y] - cost);
if(new_t >= 0) pq.push({{new_t, visited + 1}, {x-1, y}});
}
if(y && grid[x][y-1] != 'T') {
new_t = min(t, depth[x][y-1] - cost);
if(new_t >= 0) pq.push({{new_t, visited + 1}, {x, y-1}});
}
if(x+1<n && grid[x+1][y] != 'T') {
new_t = min(t, depth[x+1][y] - cost);
if(new_t >= 0) pq.push({{new_t, visited + 1}, {x+1, y}});
}
if(y+1<n && grid[x][y+1] != 'T') {
new_t = min(t, depth[x][y+1] - cost);
if(new_t >= 0) pq.push({{new_t, visited + 1}, {x, y+1}});
}
}
cout << -1 << endl;
}
signed main()
{
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int t=1;
while(t--) solve();
return 0;
}
