#include <bits/stdc++.h>
#define FIXED_FLOAT(x) std::fixed <<std::setprecision(20) << (x)
#define all(v) (v).begin(), (v).end()
using namespace std;
#define forn(i,n) for (int i = 0; i < (n); ++i)
#define rforn(i, n) for(int i = (n) - 1;i >= 0;--i)
using ll = long long;
int mod = (ll)1e9 + 7;
#define PI acos(-1)
typedef pair<int, int> pairs;
const int INF = 1e9 + 1;
const int N = 2e5 + 100;
const double eps = 1e-7;
template <class T> using V = vector<T>;
template <class T> using VV = V<V<T>>;
template <typename XPAX>
void ckma(XPAX &x, XPAX y) {
x = (x < y ? y : x);
}
template <typename XPAX>
void ckmi(XPAX &x, XPAX y) {
x = (x > y ? y : x);
}
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
void solve() {
int n;
cin >> n;
int s;
cin >> s;
queue<pairs> q;
V<string> c(n);
forn(i, n) {
cin >> c[i];
//debug(c[i]);
}
auto valid = [&](int i, int j) {
return (i < n && j < n && i > -1 && j > -1 && c[i][j] != 'T');
};
int sx, sy;
int tx, ty;
V<pairs> directions{{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
auto dv = [&](int x) {
return x / s;
};
VV<int> bee(n, V<int>(n, INF));
forn(i, n) forn(j, n) {
if(c[i][j] == 'H') {
q.push({i, j});
bee[i][j] = 0;
}
if(c[i][j] == 'D') {
tx = i;
ty = j;
}
if(c[i][j] == 'M') {
sx = i;
sy = j;
}
}
// debug(bee);
while(q.size()) {
int i = q.front().first;
int j = q.front().second;
q.pop();
for(auto dir : directions) {
int ei = i + dir.first;
int ej = j + dir.second;
if(valid(ei, ej) && bee[ei][ej] == INF && c[ei][ej] == 'G') {
bee[ei][ej] = bee[i][j] + 1;
q.push({ei, ej});
}
}
}
auto ck = [&](int mid) -> bool {
VV<int> dis(n, V<int>(n, -1));
dis[sx][sy] = 0;
queue<pairs> q;
q.push({sx, sy});
while(q.size()) {
int i = q.front().first;
int j = q.front().second;
q.pop();
for(auto dir : directions) {
int ei = i + dir.first;
int ej = j + dir.second;
if(valid(ei, ej) && dis[ei][ej] == -1 && bee[ei][ej] > dv(dis[i][j] + 1) + mid) {
dis[ei][ej] = dis[i][j] + 1;
q.push({ei, ej});
}
}
}
//debug(dis);
return (dis[tx][ty] != -1);
};
int low = 0;
int high = bee[sx][sy] - 1;
while(low < high) {
int mid = (low + high + 1) / 2;
if(ck(mid))
low = mid;
else high = mid - 1;
}
cout << (ck(low) ? low : -1) << '\n';
}
void test_case() {
int t;
cin >> t;
forn(p, t) {
//cout << "Case #" << p + 1 << ": ";
solve();
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
solve();
}
