#include <bits/stdc++.h>
using namespace std;
int greedy_scan(const vector<string>& v, int n, int m, bool horizontal_first) {
vector<char> used(n * m, 0);
int cnt = 0;
if (horizontal_first) {
for (int i = 0; i < n; ++i)
for (int j = 0; j + 2 < m; ++j)
if (!used[i*m + j] && !used[i*m + (j+1)] && !used[i*m + (j+2)] &&
v[i][j]=='R' && v[i][j+1]=='G' && v[i][j+2]=='W') {
used[i*m + j] = used[i*m + (j+1)] = used[i*m + (j+2)] = 1;
++cnt;
}
for (int i = 0; i + 2 < n; ++i)
for (int j = 0; j < m; ++j)
if (!used[i*m + j] && !used[(i+1)*m + j] && !used[(i+2)*m + j] &&
v[i][j]=='R' && v[i+1][j]=='G' && v[i+2][j]=='W') {
used[i*m + j] = used[(i+1)*m + j] = used[(i+2)*m + j] = 1;
++cnt;
}
}
else {
for (int i = 0; i + 2 < n; ++i)
for (int j = 0; j < m; ++j)
if (!used[i*m + j] && !used[(i+1)*m + j] && !used[(i+2)*m + j] &&
v[i][j]=='R' && v[i+1][j]=='G' && v[i+2][j]=='W') {
used[i*m + j] = used[(i+1)*m + j] = used[(i+2)*m + j] = 1;
++cnt;
}
for (int i = 0; i < n; ++i)
for (int j = 0; j + 2 < m; ++j)
if (!used[i*m + j] && !used[i*m + (j+1)] && !used[i*m + (j+2)] &&
v[i][j]=='R' && v[i][j+1]=='G' && v[i][j+2]=='W') {
used[i*m + j] = used[i*m + (j+1)] = used[i*m + (j+2)] = 1;
++cnt;
}
}
return cnt;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m;
if (!(cin >> n >> m)) return 0;
vector<string> v(n);
for (int i = 0; i < n; ++i) cin >> v[i];
if (n <= 0 || m <= 0) {
cout << 0 << '\n';
return 0;
}
int maybeans = max(greedy_scan(v, n, m, true), greedy_scan(v, n, m, false));
vector<array<int,3>> seg;
for (int i = 0; i < n; ++i) {
for (int j = 0; j + 2 < m; ++j) {
if (v[i][j]=='R' && v[i][j+1]=='G' && v[i][j+2]=='W') {
seg.push_back({i*m + j, i*m + (j+1), i*m + (j+2)});
}
}
}
for (int i = 0; i + 2 < n; ++i) {
for (int j = 0; j < m; ++j) {
if (v[i][j]=='R' && v[i+1][j]=='G' && v[i+2][j]=='W') {
seg.push_back({i*m + j, (i+1)*m + j, (i+2)*m + j});
}
}
}
int P = (int)seg.size();
if (P == 0) {
cout << 0 << '\n';
return 0;
}
vector<int> cc(n * m, 0);
for (int id = 0; id < P; ++id) {
auto &s = seg[id];
cc[s[0]]++;
cc[s[1]]++;
cc[s[2]]++;
}
priority_queue<pair<int,int>, vector<pair<int,int>>, greater<pair<int,int>>> pq;
for (int id = 0; id < P; ++id) {
auto &s = seg[id];
int loss = cc[s[0]] + cc[s[1]] + cc[s[2]] - 3;
pq.push({loss, id});
}
vector<char> ac(n*m, 0);
vector<char> segt(P, 0);
int chosen = 0;
while (!pq.empty()) {
auto cur = pq.top(); pq.pop();
int id = cur.second;
if (segt[id]) continue;
auto &s = seg[id];
if (ac[s[0]] || ac[s[1]] || ac[s[2]]) continue;
int curr_loss = cc[s[0]] + cc[s[1]] + cc[s[2]] - 3;
if (curr_loss != cur.first) {
pq.push({curr_loss, id});
continue;
}
segt[id] = 1;
++chosen;
ac[s[0]] = ac[s[1]] = ac[s[2]] = 1;
cc[s[0]] = max(0, cc[s[0]] - 1);
cc[s[1]] = max(0, cc[s[1]] - 1);
cc[s[2]] = max(0, cc[s[2]] - 1);
}
int mightbeans = chosen;
int ans = max(maybeans, mightbeans);
cout << ans << '\n';
return 0;
}
