//#pragma GCC optimize("no-stack-protector")
//#pragma comment(linker, "/stack:200000000")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
#define all(x) x.begin(), x.end()
template <typename T1, typename T2> inline void chkmin(T1 &x, const T2 & y) {if (x > y) x = y;}
template <typename T1, typename T2> inline void chkmax(T1 &x, const T2 & y) {if (x < y) x = y;}
const int MAXN = 3001;
char table[MAXN][MAXN];
vector<int> g[MAXN];
int n, m;
void read() {
cin >> n >> m;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
cin >> table[i][j];
}
}
}
bool check_right(int i, int j) {
return j >= 0 && j + 2 < m && i >= 0 && i < n && table[i][j] == 'R' && table[i][j + 1] == 'G' && table[i][j + 2] == 'W';
}
bool check_down(int i, int j) {
return j >= 0 && j < m && i >= 0 && i + 2 < n && table[i][j] == 'R' && table[i + 1][j] == 'G' && table[i + 2][j] == 'W';
}
int cnt;
int used[MAXN];
int mt[MAXN];
bool dfs(int v, int c) {
if (used[v] == c) return false;
used[v] = c;
for (auto i : g[v]) {
if (mt[i] == -1) {
mt[i] = v;
return true;
}
}
for (auto i : g[v]) {
if (dfs(mt[i], c)) {
mt[i] = v;
return true;
}
}
return false;
}
void build() {
cnt = 0;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
cnt += check_right(i, j);
cnt += check_down(i, j);
}
}
}
int ans;
void calc(int s) {
int i = 0;
int j = s;
if (j >= m) {
j = m - 1;
i = s - (m - 1);
}
int pos = 0;
for (; i < n && j >= 0; i++, j--, pos++) {
if (!check_down(i, j)) continue;
if (check_right(i, j)) {
g[pos].push_back(pos);
}
if(check_right(i + 1, j - 1)) {
g[pos].push_back(pos + 1);
}
if (check_right(i + 2, j - 2)) {
g[pos].push_back(pos + 2);
}
}
for (int i = 0; i < pos; i++) {
mt[i] = used[i] = -1;
}
int c = 0;
for (int i = 0; i < pos; i++) {
dfs(i, c++);
}
for (int i = 0; i < pos; i++) {
if (mt[i] != -1) {
ans--;
}
}
for (int i = 0; i < pos; i++)
g[i].clear();
}
void run() {
build();
ans = cnt;
for (int i = 0; i < n + m - 1; i++)
calc(i);
}
void write() {
cout << ans << endl;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
read();
run();
write();
return 0;
}
