#include <bits/stdc++.h>
#include <random>
using namespace std;
using ll = int;
using ld = long double;
ll INF = 1e9;
vector<vector<ll>> g;
vector<ll> p;
vector<ll> used;
ll tt = 1;
bool kun(ll v) {
if (used[v] == tt) {
return false;
}
used[v] = tt;
for (ll i = 0; i < g[v].size(); i++) {
ll to = g[v][i];
if (p[to] == -1 || kun(p[to])) {
p[to] = v;
return true;
}
}
return false;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
ll n, m;
cin >> n >> m;
vector<string> s(n);
vector<vector<ll>> pref(n, vector<ll>(m));
vector<vector<vector<ll>>> all(n, vector<vector<ll>>(m));
for (ll i = 0; i < n; i++) {
cin >> s[i];
}
ll cnt1 = 0;
for (ll i = 0; i < n; i++) {
for (ll j = 0; j < m; j++) {
if (s[i][j] == 'R') {
if (j + 2 < m) {
if (s[i][j + 1] == 'G' && s[i][j + 2] == 'W') {
all[i][j].push_back(cnt1);
all[i][j + 1].push_back(cnt1);
all[i][j + 2].push_back(cnt1);
cnt1++;
}
}
}
}
}
ll cnt2 = 0;
for (ll i = 0; i < n; i++) {
for (ll j = 0; j < m; j++) {
if (s[i][j] == 'R') {
if (i + 2 < n) {
if (s[i + 1][j] == 'G' && s[i + 2][j] == 'W') {
vector<ll> q;
for (ll e = 0; e < all[i][j].size(); e++) {
q.push_back(all[i][j][e]);
}
for (ll e = 0; e < all[i + 1][j].size(); e++) {
q.push_back(all[i + 1][j][e]);
}
for (ll e = 0; e < all[i + 2][j].size(); e++) {
q.push_back(all[i + 2][j][e]);
}
if (!q.empty()) {
std::sort(q.begin(), q.end());
q.resize(std::unique(q.begin(), q.end()) - q.begin());
}
g.push_back(q);
cnt2++;
}
}
}
}
}
p.assign(cnt1 + 1, -1);
used.assign(cnt2 + 1, 0);
ll col = cnt1 + cnt2;
ll d = 0;
for (ll i = 0; i < cnt2; i++) {
tt++;
if (kun(i)) {
d++;
}
}
cout << col - d;
}
