#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, int> pli;
typedef pair<ll, ll> pll;
const int N = 3e3 + 1;
int n, m, id[N][N][2], cnt;
char c[N][N];
vector<vector<int>> g;
vector<int> deg;
vector<bool> vst;
inline bool check(char x, char y, char z) {
return (x == 'R' && y == 'G' && z == 'W');
}
void solve() {
cin >> n >> m;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m; ++j)
cin >> c[i][j];
}
for (int i = 1; i + 2 <= n; ++i) {
for (int j = 1; j <= m; ++j) {
if (check(c[i][j], c[i + 1][j], c[i + 2][j]))
id[i][j][0] = ++cnt;
}
}
for (int i = 1; i <= n; ++i) {
for (int j = 1; j + 2 <= m; ++j) {
if (check(c[i][j], c[i][j + 1], c[i][j + 2]))
id[i][j][1] = ++cnt;
}
}
g.resize(cnt + 1);
deg.resize(cnt + 1, 0);
vst.resize(cnt + 1, 0);
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m; ++j) {
if (!id[i][j][1]) continue;
if (id[i][j][0]) {
g[id[i][j][0]].pb(id[i][j][1]);
g[id[i][j][1]].pb(id[i][j][0]);
++deg[id[i][j][0]], ++deg[id[i][j][1]];
}
if (i - 1 > 0) {
if (id[i - 1][j + 1][0]) {
g[id[i - 1][j + 1][0]].pb(id[i][j][1]);
g[id[i][j][1]].pb(id[i - 1][j + 1][0]);
++deg[id[i - 1][j + 1][0]], ++deg[id[i][j][1]];
}
}
if (i - 2 > 0) {
if (id[i - 2][j + 2][0]) {
g[id[i - 2][j + 2][0]].pb(id[i][j][1]);
g[id[i][j][1]].pb(id[i - 2][j + 2][0]);
++deg[id[i - 2][j + 2][0]], ++deg[id[i][j][1]];
}
}
}
}
int ans = 0;
set<pii> st;
for (int i = 1; i <= cnt; ++i) {
if (!deg[i]) {
++ans;
continue;
}
st.insert(mp(deg[i], i));
}
if (n * m >= 8000000) {
cout << ans;
return;
}
while (!st.empty()) {
++ans;
auto it = st.begin();
pii x = *it;
int u = x.se;
st.erase(it);
vst[u] = true;
for (int v: g[u]) {
if (vst[v]) continue;
st.erase(st.find(mp(deg[v], v)));
vst[v] = true;
for (int q: g[v]) {
if (!vst[q]) {
st.erase(st.find(mp(deg[q], q)));
--deg[q];
st.insert(mp(deg[q], q));
}
}
}
}
cout << ans;
}
int main() {
cin.tie(NULL);
ios_base::sync_with_stdio(false);
solve();
return 0;
}
