#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>());
}
}
}
int id = 0;
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'){
if(row[i][j] != -1){
g[row[i][j]].emplace_back(id);
}
if(row[i + 1][j - 1] != -1){
g[row[i + 1][j - 1]].emplace_back(id);
}
if(j > 2 && row[i + 2][j - 2] != -1){
g[row[i + 2][j - 2]].emplace_back(id);
}
id++;
}
}
}
vector<int>match(id, -1), f(g.size(), -1);
vector<bool>in(g.size(), false);
int cnt_iter = 0;
auto kuhn = [&] (auto&& self, int u) -> bool{
if(f[u] == cnt_iter){
return false;
}
f[u] = cnt_iter;
for(int& v : g[u]){
if(match[v] == -1 || self(self, match[v])){
match[v] = u;
return true;
}
}
return false;
};
for(bool run = true; run; cnt_iter++){
run = false;
for(int i = 0; i < g.size(); i++){
if(!in[i] && kuhn(kuhn, i)){
in[i] = run = true;
id--;
}
}
}
cout << int(g.size()) + id;
}
}
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){
sub23::solve();
}
else if(n <= 10 && m <= 10){
sub23::solve();
}
else{
sub23::solve();
}
}
