#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define pb push_back
#define pa pair<int, int>
#define pall pair<ll, int>
#define fi first
#define se second
#define TASK "test"
#define all(x) x.begin(), x.end()
using namespace std;
template<typename T1, typename T2> bool mini (T1 &a, T2 b) {if(a > b) a = b; else return 0; return 1;}
template<typename T1, typename T2> bool maxi (T1 &a, T2 b) {if(a < b) a = b; else return 0; return 1;}
const int MOD = 1e9 + 7;
const int LOG = 20;
const int maxn = 8e2 + 7;
const ll oo = 1e17 + 69;
int n, s, xm, ym, xd, yd, vis[maxn][maxn];
char a[maxn][maxn];
pa d[] = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
bool bfs(int time) {
memset(vis, 0, sizeof vis);
deque<pa> q;
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++)
if(a[i][j] == 'H') {
q.pb({i, j});
vis[i][j] = 2;
}
q.push_front({xm, ym});
vis[xm][ym] = 1;
int cnt = 0;
bool ok = (time == 0);
while(!q.empty()) {
int u, v;
vector<pa> cur;
cnt++;
if(cnt <= time && !ok) {
while(vis[q.back().fi][q.back().se] == 2) {
u = q.back().fi, v = q.back().se;
q.pop_back();
cur.pb({u, v});
}
}
if(ok) {
if(cnt <= s) {
while(vis[q.front().fi][q.front().se] == 1) {
u = q.front().fi, v = q.front().se;
q.pop_front();
cur.pb({u, v});
}
} else if(cnt == s + 1) {
while(vis[q.back().fi][q.back().se] == 2) {
u = q.back().fi, v = q.back().se;
q.pop_back();
cur.pb({u, v});
}
cnt = 0;
}
}
vector<pa> nxt;
bool type = 0;
for(auto e:cur) {
u = e.fi, v = e.se;
for(int k = 0; k < 4; k++) {
int x = u + d[k].fi;
int y = v + d[k].se;
if(x < 0 || x == n || y < 0 || y == n || a[x][y] == 'T' || vis[x][y]) continue;
if(vis[u][v] == 1 && a[x][y] == 'H') continue;
if(vis[u][v] == 2 && a[x][y] == 'D') continue;
vis[x][y] = vis[u][v];
if(vis[x][y] == 1) type = 1;
nxt.pb({x, y});
}
}
for(auto e:nxt) {
if(type) q.push_front(e);
else q.pb(e);
}
if(cnt == time && !ok) {
ok = 1;
cnt = 0;
}
}
// for(int i = 0; i < n; i++) {
// for(int j = 0; j < n; j++) cout<<vis[i][j]<<" ";
// cout<<"\n";
// }
return (vis[xd][yd] == 1);
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
//freopen(TASK".inp", "r", stdin);
//freopen(TASK".out", "w", stdout);
cin>>n>>s;
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++) {
cin>>a[i][j];
if(a[i][j] == 'M') {
xm = i;
ym = j;
}
if(a[i][j] == 'D') {
xd = i;
yd = j;
}
}
int l = 0, r = n * n, mid, res = -1;
while(l <= r) {
mid = l + r >> 1;
if(bfs(mid)) {
l = mid + 1;
res = mid;
} else r = mid - 1;
}
cout<<res;
return 0;
}
