#include <bits/stdc++.h>
using namespace std;
vector <int> adiacenta[1000001];
int inlocuitor[3000][3000] , pereche[3000001] , moment[1000001];
char matrice[3000][3001];
inline bool CautaPereche (const int nod)
{
if (moment[nod] == moment[0])
{ return false; }
moment[nod] = moment[0];
for (auto& vecin : adiacenta[nod]) {
if (!pereche[vecin])
{
pereche[vecin] = nod;
pereche[nod] = vecin;
return true;
}
}
for (auto& vecin : adiacenta[nod]) {
if (CautaPereche(pereche[vecin]))
{
pereche[vecin] = nod;
pereche[nod] = vecin;
return true;
}
}
return false;
}
int main ()
{
ios :: sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
int linii , coloane;
cin >> linii >> coloane;
for (int linie = 0 ; linie < linii ; linie++)
{ cin >> matrice[linie]; }
int numar_noduri_1 = 0;
for (int linie = 0 ; linie < linii ; linie++) {
for (int coloana = 0 ; coloana < coloane ; coloana++) {
if (matrice[linie][coloana] == 'R' && ((coloana + 2 < coloane && matrice[linie][coloana + 1] == 'G' && matrice[linie][coloana + 2] == 'W') || (linie + 2 < linii && matrice[linie + 1][coloana] == 'G' && matrice[linie + 2][coloana] == 'W')))
{ inlocuitor[linie][coloana] = ++numar_noduri_1; }
}
}
int numar_noduri_2 = 0;
for (int linie = 0 ; linie < linii ; linie++) {
for (int coloana = 0 ; coloana < coloane ; coloana++) {
if (matrice[linie][coloana] == 'W' && ((coloana - 2 >= 0 && matrice[linie][coloana - 1] == 'G' && matrice[linie][coloana - 2] == 'R') || (linie - 2 >= 0 && matrice[linie - 1][coloana] == 'G' && matrice[linie - 2][coloana] == 'R')))
{ inlocuitor[linie][coloana] = ++numar_noduri_2 + numar_noduri_1; }
}
}
for (int linie = 0 ; linie < linii ; linie++) {
for (int coloana = 0 ; coloana < coloane ; coloana++) {
if (matrice[linie][coloana] == 'R' && inlocuitor[linie][coloana])
{
if (coloana + 2 < coloane && matrice[linie][coloana + 1] == 'G' && matrice[linie][coloana + 2] == 'W')
{ adiacenta[inlocuitor[linie][coloana]].push_back(inlocuitor[linie][coloana + 2]); }
if (linie + 2 < linii && matrice[linie + 1][coloana] == 'G' && matrice[linie + 2][coloana] == 'W')
{ adiacenta[inlocuitor[linie][coloana]].push_back(inlocuitor[linie + 2][coloana]); }
}
}
}
int cuplaj = 0;
while (true)
{
moment[0]++;
bool gasit = false;
for (int nod = 1 ; nod <= numar_noduri_1 ; nod++) {
if (!pereche[nod] && CautaPereche(nod))
{ gasit = true; cuplaj++; }
}
if (!gasit)
{ break; }
}
cout << cuplaj;
return 0;
}
