#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
using ll = long long;
using vi = vector<int>;
using pii = pair<int, int>;
bool Mbe;
constexpr int N = 1e2 + 9;
constexpr int M = 1 << 10;
constexpr double eps = 1e-5;
constexpr int mod = 1e8;
constexpr int inf = 0x3f3f3f3f;
//mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rnd(2024);
int rd(int l, int r) {
	return rnd() % (r - l + 1) + l;
}
int read();
void write(ll x);
int n, m, s[M], cnt, g[N], num[M], f[2][M][M];
bool Med; 
/*------------------------------------------------------------------------*/
int main() {
	fprintf(stderr, "%.3lf MB\n", (&Mbe - &Med) / 1048576.0);
	ios::sync_with_stdio(0), cin.tie(nullptr), cout.tie(nullptr);
	cin >> n >> m;
	for (int i = 1; i <= n; i++) {
		for (int j = 0; j < m; j++) {
			char ch; cin >> ch;
			if (ch == 'P') g[i] += (1 << m - j - 1);
		}
	}
	for (int i = 0; i < (1 << m); i++) {
		if (!(i & i << 1) && !(i & i << 2)) {
			s[cnt++] = i;
			num[i] = __builtin_popcount(i);
		}
	}
	for (int i = 1; i <= n + 2; i++) 
		for (int a = 0; a < cnt; a++)
			for (int b = 0; b < cnt; b++) 
				for (int c = 0; c < cnt; c++)
					if (!(s[a] & s[b]) && !(s[b] & s[c]) && !(s[a] & s[c]) && (s[a] & g[i]) == s[a] && (s[b] & g[i - 1]) == s[b]) 
						f[i & 1][a][b] = max(f[i & 1][a][b], f[i - 1 & 1][b][c] + num[s[a]]);
	cout << f[n + 2 & 1][0][0];
	cerr << "\n" << 1e3 * clock() / CLOCKS_PER_SEC << " ms\n";
	return 0;
}
/*------------------------------------------------------------------------*/
int read() {
	int x = 0, w = 1;
	char ch = 0;
	while (ch < '0' || ch > '9') {
		if (ch == '-') w = -1;
		ch = getchar();
	}
	while (ch >= '0' && ch <= '9') {
		x = x * 10 + (ch - '0');
		ch = getchar();
	}
	return x * w;
}
void write(ll x) {
	if (x < 0) x = -x, putchar('-');
	static int sta[35];
	int top = 0;
	do {
		sta[top++] = x % 10, x /= 10;
	} while (x);
	while (top) putchar(sta[--top] + 48);
}