#include<bits/stdc++.h>
#define taskname "C"
using namespace std;
template<class T>void maximize(T& a, T b){
if(a < b){
a = b;
}
}
int n, m;
namespace sub1{
void solve(){
vector<int>dp(1 << (n * m), -1);
vector<vector<char>>a(n, vector<char>(m));
for(int i = 0; i < n; i++){
for(int j = 0; j < m; j++){
cin >> a[i][j];
}
}
auto solve = [&] (auto&& self, vector<vector<bool>>state) -> int{
int mask = 0;
for(int i = 0, p = 0; i < n; i++){
for(int j = 0; j < m; j++, p++){
if(state[i][j]){
mask |= 1 << p;
}
}
}
int& ans = dp[mask];
if(ans != -1){
return ans;
}
for(int i = ans = 0; i < n; i++){
for(int j = 0; j + 2 < m; j++){
if(state[i][j] && state[i][j + 1] && state[i][j + 2]){
if(a[i][j] == 'R' && a[i][j + 1] == 'G' && a[i][j + 2] == 'W'){
state[i][j] = state[i][j + 1] = state[i][j + 2] = false;
maximize(ans, self(self, state) + 1);
state[i][j] = state[i][j + 1] = state[i][j + 2] = true;
}
}
}
}
for(int i = 0; i + 2 < n; i++){
for(int j = 0; j < m; j++){
if(state[i][j] && state[i + 1][j] && state[i + 2][j]){
if(a[i][j] == 'R' && a[i + 1][j] == 'G' && a[i + 2][j] == 'W'){
state[i][j] = state[i + 1][j] = state[i + 2][j] = false;
maximize(ans, self(self, state) + 1);
state[i][j] = state[i + 1][j] = state[i + 2][j] = true;
}
}
}
}
return ans;
};
cout << solve(solve, vector<vector<bool>>(n, vector<bool>(m, true)));
}
}
namespace sub23{
void solve(){
vector<vector<char>>a(n + 1, vector<char>(m + 1));
for(int i = 1; i <= n; i++){
for(int j = 1; j <= m; j++){
cin >> a[i][j];
}
}
vector<vector<int>>g, row(n + 1, vector<int>(m + 1, -1));
for(int i = 1, id = 0; i <= n; i++){
for(int j = 1; j + 1 < m; j++){
if(a[i][j] == 'R' && a[i][j + 1] == 'G' && a[i][j + 2] == 'W'){
row[i][j] = g.size();
g.emplace_back(vector<int>());
}
}
}
auto add_edge = [&] (int u, int v){
g[u].emplace_back(v);
g[v].emplace_back(u);
};
for(int i = 1; i + 1 < n; i++){
for(int j = 1; j <= m; j++){
if(a[i][j] == 'R' && a[i + 1][j] == 'G' && a[i + 2][j] == 'W'){
int id = g.size();
g.emplace_back(vector<int>());
if(row[i][j] != -1){
add_edge(row[i][j], id);
}
if(row[i + 1][j - 1] != -1){
add_edge(row[i + 1][j - 1], id);
}
if(j > 2 && row[i + 2][j - 2] > -1){
add_edge(row[i + 2][j - 2], id);
}
}
}
}
vector<vector<int>>dp(g.size(), vector<int>(2, -1));
auto dfs = [&] (auto&& self, int s, int p) -> void{
dp[s][0] = 0;
dp[s][1] = 1;
for(int& d : g[s]){
if(d != p){
self(self, d, s);
dp[s][0] += max(dp[d][0], dp[d][1]);
dp[s][1] += dp[d][0];
}
}
};
int ans = 0;
for(int i = 0; i < g.size(); i++){
if(dp[i][0] == -1){
dfs(dfs, i, -1);
ans += max(dp[i][0], dp[i][1]);
}
}
cout << ans;
}
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
if(fopen(taskname".inp", "r")){
freopen(taskname".inp", "r", stdin);
}
cin >> n >> m;
if(n <= 4 && m <= 4){
sub1::solve();
}
else{
sub23::solve();
}
}
