#include <bits/stdc++.h> using namespace std; #define f first #define s second #define mp make_pair int n, S, start_i, start_j, end_i, end_j; vector<vector<char>> grid(1001, vector<char>(1001)); vector<vector<int>> bdist(1001, vector<int>(1001, 1e9)); vector<int> dx = {0, 0, -1, 1}, dy = {-1, 1, 0, 0}; bool targeted(int mdist, int bdist){ return mdist / S >= bdist; } bool in_bounds(int x, int y){ return x >= 0 && x < n && y >= 0 && y < n; } bool check(int val){ queue<pair<int, int>> q; q.push(mp(start_i, start_j)); vector<vector<int>> dist(n, vector<int>(n, 1e9)); dist[start_i][start_j] = 0; while(!q.empty()){ auto top = q.front(); q.pop(); for(int i = 0; i < 4; i++){ int x = top.f+dx[i]; int y = top.s+dy[i]; if(in_bounds(x, y) && grid[x][y] == 'G' && dist[x][y] == 1e9 && !targeted(dist[top.f][top.s] + 1, bdist[x][y] - val)){ dist[x][y] = dist[top.f][top.s] + 1; q.push(mp(x, y)); } } } // corner case check for(int i = 0; i < 4; i++){ int x = end_i+dx[i], y = end_j+dy[i]; if(in_bounds(x, y)){ dist[end_i][end_j] = min(dist[end_i][end_j], dist[x][y]); } } return !(dist[end_i][end_j] == 1e9); } int main(){ cin >> n >> S; queue<pair<int, int>> q; for(int i = 0; i < n; i++){ for(int j = 0; j < n; j++){ cin >> grid[i][j]; if(grid[i][j] == 'H'){ q.push(mp(i, j)); bdist[i][j] = 0; } else if(grid[i][j] == 'M'){ start_i = i; start_j = j; } else if(grid[i][j] == 'D'){ end_i = i; end_j = j; } } } while(!q.empty()){ auto top = q.front(); q.pop(); for(int i = 0; i < 4; i++){ int x = top.f + dx[i]; int y = top.s + dy[i]; if(in_bounds(x, y) && bdist[x][y] == 1e9){ bdist[x][y] = bdist[top.f][top.s] + 1; q.push(mp(x, y)); } } } int l = 0, r = 1e9, ans = -1; while(l <= r){ int mid = (l + r)/2; if(check(mid)){ ans = mid; l = mid+1; } else r = mid-1; } cout << ans << endl; }