/* Author : Mychecksdead */
#include<bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long int ll;
typedef long double ld;
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define PI 3.1415926535
#define pb push_back
#define setp() cout << setprecision(15)
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " is " << x << '\n';
const int N = 1e6+100, M = 1e5+10, F = 2147483646, K = 20;
int n, S, ax, ay, bx, by, dist[1000][1000], d[1000][1000], arr[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
string s[N];
bool vis[1000][1000];
void solve(){
cin >> n >> S;
queue<array<int, 2>> q, q1;
for(int i = 0; i < n; ++i){
cin >> s[i];
for(int j = 0; j < n; ++j){
dist[i][j] = d[i][j] = MOD;
if(s[i][j] == 'H') q.push({i, j}), dist[i][j] = 0;
else if(s[i][j] == 'M') q1.push({i, j}), d[i][j] = 0, bx = i, by = j;
else if(s[i][j] == 'D') ax = i, ay = j;
}
}
while(!q.empty()){
int x = q.front()[0], y = q.front()[1];
q.pop();
for(int i = 0; i < 4; ++i){
int a = x + arr[i][0];
int b = y + arr[i][1];
if(a>=0&&a<n&&b>=0&&b<n&&s[a][b]=='D'){
dist[a][b] = min(dist[a][b], dist[x][y] + 1);
}
if(a<0||b<0||a==n||b==n||(s[a][b]!='G'&&s[a][b]!='M')) continue;
if(dist[a][b] > dist[x][y] + 1) {
dist[a][b] = dist[x][y] + 1;
q.push({a, b});
}
}
}
while(!q1.empty()){
int x = q1.front()[0], y = q1.front()[1];
q1.pop();
for(int i = 0; i < 4; ++i){
for(int f = 1; f <= S; ++f){
int a = x + f * arr[i][0];
int b = y + f * arr[i][1];
if(a<0||b<0||a>=n||b>=n||(s[a][b]!='G'&&s[a][b]!='M'&&s[a][b]!='D')||d[a][b] < d[x][y] + 1) break;
d[a][b] = d[x][y] + 1;
q1.push({a, b});
}
}
}
int l = 0, r = n*n, ans = -1;
while(l <= r){
int m = (l+r)>>1;
bool ok = 0;
for(int i = 0; i < n; ++i) for(int j = 0; j < n; ++j) vis[i][j] = 0;
q.push({ax, ay});
vis[ax][ay] = 1;
while(!q.empty()){
int x = q.front()[0], y = q.front()[1];
q.pop();
if(dist[x][y] - m <= d[x][y]){
continue;
}
if(x == bx && y == by){
ok = 1;
break;
}
for(int i = 0; i < 4; ++i){
for(int f = 1; f <= S; ++f){
int a = x + f * arr[i][0];
int b = y + f * arr[i][1];
if(a<0||b<0||a>=n||b>=n||(s[a][b]!='G'&&s[a][b]!='M')||vis[a][b]) break;
vis[a][b] = 1;
q.push({a, b});
}
}
}
if(ok){
ans = m;
l = m + 1;
}else r = m - 1;
}
cout << ans;
}
int main(){
cin.tie(0); ios::sync_with_stdio(0);
int T = 1, aa;
// cin >> T;aa=T;
while(T--){
// cout << "Case #" << aa-T << ": ";
solve();
cout << '\n';
}
return 0;
}
