#include <bits/stdc++.h>
#define ll long long int
#define pb push_back
#define fi first
#define se second
using namespace std;
char a[20][20];
bool b[20][20];
int n, m, mx = 0;
void dfs(int i, int j) {
if (i == n) {i = 0; j++;}
if (j == m) {
int cnt = 0;
for (int ii = 0; ii < n; ii++) {
for (int jj = 0; jj < m; jj++) {
if (b[ii][jj]) cnt++;
}
}
cnt /= 3;
mx = max(mx, cnt); return;
}
if (a[i][j] == 'R' && a[i+1][j] == 'G' && a[i+2][j] == 'W') {
if (!b[i][j] && !b[i+1][j] && !b[i+2][j]) {
b[i][j] = 1; b[i+1][j] = 1; b[i+2][j] = 1;
dfs(i+1, j);
b[i][j] = 0; b[i+1][j] = 0; b[i+2][j] = 0;
}
}
if (a[i][j] == 'R' && a[i][j+1] == 'G' && a[i][j+2] == 'W') {
if (!b[i][j] && !b[i][j+1] && !b[i][j+2]) {
b[i][j] = 1; b[i][j+1] = 1; b[i][j+2] = 1;
dfs(i+1, j);
b[i][j] = 0; b[i][j+1] = 0; b[i][j+2] = 0;
}
}
dfs(i+1, j);
}
int main() {
cin >> n >> m;
for (int i = 0; i < 20; i++) {
for (int j = 0; j < 20; j++) {
a[i][j] = '.';
}
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
cin >> a[i][j];
}
}
dfs(0, 0);
cout << mx;
return 0;
}
