#include <iostream>
#include <iomanip>
#include <vector>
#include <cmath>
#include <algorithm>
#include <set>
#include <queue>
#include <map>
#include <unordered_map>
#include <stack>
#include <bitset>
#include <string>
#include <cstring>
#include <iterator>
#include <random>
#define ll int
#define ld long double
#define inf (ll)(2*1e18)
#define sort(a) sort(a.begin(), a.end())
#define reverse(a) reverse(a.begin(), a.end())
#define pb push_back
#define endl "\n"
using namespace std;
bool DFS(ll id, vector<vector<ll>>& b, vector<ll>& go, vector<bool>& visited){
if(visited[id]) return false;
visited[id] = true;
for(auto el: b[id]){
if(go[el] == -1){
go[el] = id;
return true;
}
if(DFS(go[el], b, go, visited)){
go[el] = id;
return true;
}
}
return false;
}
void solve(){
ll n, m, i, j, res=0, cnt=0, cnt1=0;
cin>>n>>m;
vector<vector<char>> a(n, vector<char>(m));
vector<vector<ll>> c(n, vector<ll>(m, -1));
vector<vector<ll>> b;
for(i=0;i<n;++i){
for(j=0;j<m;++j){
cin>>a[i][j];
}
}
for(i=0;i<n-2;++i){
for(j=0;j<m;++j){
if(a[i][j] == 'R' and a[i+1][j] == 'G' and a[i+2][j] == 'W'){
c[i][j] = cnt;
c[i+1][j] = cnt;
c[i+2][j] = cnt;
++cnt;
++cnt1;
b.pb(vector<ll>());
}
}
}
for(i=0;i<n;++i){
for(j=0;j<m-2;++j){
if(a[i][j] == 'R' and a[i][j+1] == 'G' and a[i][j+2] == 'W'){
b.pb(vector<ll>());
if(c[i][j] != -1){
b[cnt].pb(c[i][j]);
b[c[i][j]].pb(cnt);
}
if(c[i][j+1] != -1){
b[cnt].pb(c[i][j+1]);
b[c[i][j+1]].pb(cnt);
}
if(c[i][j+2] != -1){
b[cnt].pb(c[i][j+2]);
b[c[i][j+2]].pb(cnt);
}
++cnt;
}
}
}
vector<ll> go(cnt, -1);
for(i=0;i<cnt1;++i){
vector<bool> visited(cnt1, false);
DFS(i, b, go, visited);
}
for(i=cnt1;i<cnt;++i){
if(go[i] != -1) ++res;
}
cout<<cnt - res<<endl;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
srand(time(nullptr));
ll t=1;
// cin>>t;
for(;t>0;--t){
solve();
}
return 0;
}
