#include "bits/stdc++.h"
using namespace std;
using ll = long long;
// RGW
int n, m;
string s[3005];
int a[3005][3005], b[3005][3005];
vector<int> va[9000005];
int ma[9000005], mb[9000005];
bool visitb[9000005];
int cnt, cnt2;
stack<int> clrS;
bool dfs(int cur) {
for (int nxt : va[cur]) {
if (!visitb[nxt]) {
visitb[nxt] = true;
clrS.push(nxt);
if (mb[nxt] == 0 || dfs(mb[nxt])) {
ma[cur] = nxt;
mb[nxt] = cur;
return true;
}
}
}
return false;
}
int bipartite_matching() {
int ret = 0;
for (int i = 1; i <= cnt; i++) {
while (!clrS.empty()) {
visitb[clrS.top()] = false;
clrS.pop();
}
if (dfs(i)) ++ret;
}
return ret;
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> m;
for (int i = 0; i < n; i++) {
cin >> s[i];
}
cnt = cnt2 = 0;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (s[i][j] != 'R') continue;
if (j + 2 < m) {
if (s[i][j + 1] == 'G' && s[i][j + 2] == 'W') {
++cnt;
a[i][j] = cnt;
a[i][j + 1] = cnt;
a[i][j + 2] = cnt;
}
}
if (i + 2 < n) {
if (s[i + 1][j] == 'G' && s[i + 2][j] == 'W') {
++cnt2;
b[i][j]= cnt2;
b[i + 1][j]= cnt2;
b[i + 2][j]= cnt2;
}
}
}
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (a[i][j] != 0 && b[i][j] != 0) {
va[a[i][j]].push_back(b[i][j]);
}
}
}
cout << cnt + cnt2 - bipartite_matching() << endl;
}
