#include <bits/stdc++.h>
using namespace std;
const int MAXN = 800;
int n, s;
vector<vector<char>> grid;
vector<vector<int>> dist;
int honey;
bool reachable(int mecho, int bee) {
return (((mecho/s)+honey < bee) || (bee == -1)) && (mecho != -1);
}
void bfs(queue<pair<int, int>> &q, vector<vector<int>> &d) {
while (!q.empty()) {
int x = q.front().first;
int y = q.front().second;
q.pop();
if (x < 1 || y < 1 || x > n || y > n)
continue;
if (d[x+1][y] == -1 && grid[x+1][y] != 'X' && reachable(d[x][y]+1, dist[x+1][y])) {
q.push({x+1, y});
d[x+1][y] = d[x][y]+1;
}
if (d[x-1][y] == -1 && grid[x-1][y] != 'X' && reachable(d[x][y]+1, dist[x-1][y])) {
q.push({x-1, y});
d[x-1][y] = d[x][y]+1;
}
if (d[x][y+1] == -1 && grid[x][y+1] != 'X' && reachable(d[x][y]+1, dist[x][y+1])) {
q.push({x, y+1});
d[x][y+1] = d[x][y]+1;
}
if (d[x][y-1] == -1 && grid[x][y-1] != 'X' && reachable(d[x][y]+1, dist[x][y-1])) {
q.push({x, y-1});
d[x][y-1] = d[x][y]+1;
}
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cin >> n >> s;
grid.resize(n+2, vector<char>(n+2, '.'));
pair<int, int> start, end;
queue<pair<int, int>> q;
dist.resize(n+2, vector<int>(n+2, -1));
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
cin >> grid[i][j];
if (grid[i][j] == 'G')
grid[i][j] = '.';
else if (grid[i][j] == 'T')
grid[i][j] = 'X';
else if (grid[i][j] == 'M')
start = {i, j};
else if (grid[i][j] == 'D')
end = {i, j};
else {
q.push({i, j});
dist[i][j] = 0;
}
}
}
// distance for bees
while (!q.empty()) {
int x = q.front().first;
int y = q.front().second;
q.pop();
if (x < 1 || y < 1 || x > n || y > n)
continue;
if (dist[x+1][y] == -1 && grid[x+1][y] != 'X') {
q.push({x+1, y});
dist[x+1][y] = dist[x][y]+1;
}
if (dist[x-1][y] == -1 && grid[x-1][y] != 'X') {
q.push({x-1, y});
dist[x-1][y] = dist[x][y]+1;
}
if (dist[x][y+1] == -1 && grid[x][y+1] != 'X') {
q.push({x, y+1});
dist[x][y+1] = dist[x][y]+1;
}
if (dist[x][y-1] == -1 && grid[x][y-1] != 'X') {
q.push({x, y-1});
dist[x][y-1] = dist[x][y]+1;
}
}
int lo = 0, hi = MAXN*MAXN;
int ans = -1;
while (lo < hi) {
int mid = lo+(hi-lo)/2;
vector<vector<int>> d(n+2, vector<int>(n+2, -1));
d[start.first][start.second] = 0;
honey = mid;
q.push(start);
bfs(q, d);
if (reachable(d[end.first][end.second], dist[end.first][end.second])) {
lo = mid+1;
ans = mid;
}
else {
hi = mid;
}
}
cout << ans << '\n';
return 0;
}
