#include <cstdio>
#include <stdio.h>
#include <iostream>
#include <math.h>
#include <vector>
#include <queue>
#include <stack>
#include <deque>
#include <algorithm>
#include <utility>
#include <set>
#include <map>
#include <stdlib.h>
#include <cstring>
#include <string.h>
#include <string>
#include <sstream>
#include <assert.h>
#include <climits>
#include <sstream>
#include <numeric>
#include <time.h>
#include <limits.h>
#include <list>
#include <bitset>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <iomanip>
#include <complex>
#include <chrono>
#include <fstream>
#include <functional>
#include <unistd.h>
// #pragma GCC optimize("Ofast,no-stack-protector")
// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx,avx2,bmi,bmi2,lzcnt,popcnt")
#define lowbit(x) ((x) & -(x))
#define ml(a, b) ((1ll * (a) * (b)) % M)
#define tml(a, b) (a) = ((1ll * (a) * (b)) % M)
#define ad(a, b) ((0ll + (a) + (b)) % M)
#define tad(a, b) (a) = ((0ll + (a) + (b)) % M)
#define mi(a, b) ((0ll + M + (a) - (b)) % M)
#define tmi(a, b) (a) = ((0ll + M + (a) - (b)) % M)
#define tmin(a, b) (a) = min((a), (b))
#define tmax(a, b) (a) = max((a), (b))
#define iter(a) (a).begin(), (a).end()
#define riter(a) (a).rbegin(), (a).rend()
#define init(a, b) memset((a), (b), sizeof(a))
#define cpy(a, b) memcpy((a), (b), sizeof(a))
#define uni(a) a.resize(unique(iter(a)) - a.begin())
#define pb emplace_back
#define mpr make_pair
#define ls(i) ((i) << 1)
#define rs(i) ((i) << 1 | 1)
#define INF 0x3f3f3f3f
#define NIF 0xc0c0c0c0
#define eps 1e-9
#define F first
#define S second
#define AC cin.tie(0)->sync_with_stdio(0)
using namespace std;
typedef long long llt;
typedef pair<int, int> pii;
typedef pair<double, double> pdd;
typedef pair<llt, llt> pll;
typedef complex<double> cd;
// const int M = 998244353;
// random_device rm;
// mt19937 rg(rm());
// default_random_engine rg(rm());
// uniform_int_distribution<int> rd(INT_MIN, INT_MAX);
// uniform_real_distribution<double> rd(0, M_PI);
void db() { cerr << "\n"; }
template <class T, class... U>
void db(T a, U... b) { cerr << a << " ", db(b...); }
inline char gc()
{
const static int SZ = 1 << 16;
static char buf[SZ], *p1, *p2;
if (p1 == p2 && (p2 = buf + fread(p1 = buf, 1, SZ, stdin), p1 == p2))
return -1;
return *p1++;
}
void rd() {}
template <typename T, typename... U>
void rd(T &x, U &...y)
{
x = 0;
bool f = 0;
char c = gc();
while (!isdigit(c))
f ^= !(c ^ 45), c = gc();
while (isdigit(c))
x = (x << 1) + (x << 3) + (c ^ 48), c = gc();
f && (x = -x), rd(y...);
}
template <typename T>
void prt(T x)
{
if (x < 0)
putchar('-'), x = -x;
if (x > 9)
prt(x / 10);
putchar((x % 10) ^ 48);
}
#define vvb vector<vector<bool>>
pii operator+(const pii &a, const pii &b)
{
return mpr(a.F + b.F, a.S + b.S);
}
const pii dr[] = {pii(1, 0), pii(0, 1), pii(0, -1), pii(-1, 0)};
const int N = 805;
int n, sp;
char grid[N][N];
vvb v1, v2;
bool ok(pii p, const vvb &vd)
{
if (min(p.F, p.S) < 0 || max(p.F, p.S) >= n)
return 0;
return !vd[p.F][p.S];
}
bool slv(int lm)
{
queue<pii> q1, q2;
vector<bool>::iterator it;
v1 = v2 = vvb(n, vector<bool>(n, 0));
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
switch (grid[i][j])
{
case 'T':
v1[i][j] = v2[i][j] = 1;
break;
case 'M':
q1.push(mpr(i, j));
break;
case 'H':
q2.push(mpr(i, j)), v1[i][j] = v2[i][j] = 1;
break;
case 'D':
it = v1[i].begin() + j, v2[i][j] = 1;
}
}
}
auto move1 = [&]() -> void
{
int ln = q1.size();
while (ln--)
{
pii tp = q1.front();
q1.pop();
if (v1[tp.F][tp.S])
continue;
v1[tp.F][tp.S] = v2[tp.F][tp.S] = 1;
for (int i = 0; i < 4; i++)
{
pii cr = tp + dr[i];
if (ok(cr, v1))
q1.push(cr);
}
}
};
auto move2 = [&]() -> void
{
int ln = q2.size();
while (ln--)
{
pii tp = q2.front();
q2.pop();
for (int i = 0; i < 4; i++)
{
pii cr = tp + dr[i];
if (ok(cr, v2))
q2.push(cr), v1[cr.F][cr.S] = v2[cr.F][cr.S] = 1;
}
}
};
while (lm--)
move2();
while (!q1.empty())
{
for (int i = 0; i < sp; i++)
move1();
move2();
}
return *it;
}
signed main()
{
scanf("%d%d", &n, &sp);
for (int i = 0; i < n; i++)
scanf("%s", grid[i]);
if (!slv(0))
puts("-1"), exit(0);
int l = 0, r = n << 1;
while (l < r)
{
int m = (l + r + 1) >> 1;
if (slv(m))
l = m;
else
r = m - 1;
}
prt(l), putchar('\n');
}
