#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vii> vvii;
typedef vector<vi> vvi;
typedef pair<double, double> dodo;
#define pb(x) push_back(x)
#define mp(x, y) make_pair(x, y)
int N, M;
vvi edges;
int num_nodes = 0;
int createNode() {
edges.pb(vi());
return num_nodes++;
}
void connect(int a, int b) {
edges[a].pb(b);
edges[b].pb(a);
}
const int ARRSIZE = 3000*3000;
int parent[ARRSIZE];
bool vis[ARRSIZE] = {0};
int bfs(int x, bool b) {
int ret = 0;
queue<ii> Q;
Q.push(mp(x, (int)b));
while (!Q.empty()) {
ii a = Q.front(); Q.pop();
if (vis[a.first]) {
continue;
}
vis[a.first] = true;
ret += a.second;
for (int i = 0; i < edges[a.first].size(); i++) {
int y = edges[a.first][i];
Q.push(mp(y, !a.second));
}
}
return ret;
}
void clean(int x) {
vis[x] = false;
for (int i = 0; i < edges[x].size(); i++) {
int y = edges[x][i];
if (!vis[y]) continue;
clean(y);
}
}
int mat[3000][3000];
int touch[3000][3000][2];
void func() {
cin >> N >> M;
for (int i = 0; i < N; i++) {
string s; cin >> s;
for (int j = 0; j < M; j++) {
if (s[j] == 'R') mat[i][j] = 0;
if (s[j] == 'G') mat[i][j] = 1;
if (s[j] == 'W') mat[i][j] = 2;
}
}
for (int i = 0; i < N; i++) for (int j = 0; j < M; j++) touch[i][j][0] = touch[i][j][1] = -1;
for (int i = 0; i < N; i++) {
for (int j = 0; j < M-2; j++) {
if (mat[i][j]*9 + mat[i][j+1]*3 + mat[i][j+2]*1 == 5) {
int x = createNode();
/*if (touch[i][j].size() > 0) {
for (int k = 0; k < touch[i][j].size(); k++) connect(x, touch[i][j][k]);
}*/
if (touch[i][j][0] != -1) touch[i][j][1] = x;
else touch[i][j][0] = x;
//touch[i][j].pb(x);
/*if (touch[i][j+1].size() > 0) {
for (int k = 0; k < touch[i][j+1].size(); k++) connect(x, touch[i][j+1][k]);
}*/
if (touch[i][j+1][0] != -1) touch[i][j+1][1] = x;
else touch[i][j+1][0] = x;
//touch[i][j+1].pb(x);
/*if (touch[i][j+2].size() > 0) {
for (int k = 0; k < touch[i][j+2].size(); k++) connect(x, touch[i][j+2][k]);
}*/
if (touch[i][j+2][0] != -1) touch[i][j+2][1] = x;
else touch[i][j+2][0] = x;
//touch[i][j+2].pb(x);
}
}
}
for (int i = 0; i < N-2; i++) {
for (int j = 0; j < M; j++) {
if (mat[i][j]*9 + mat[i+1][j]*3 + mat[i+2][j]*1 == 5) {
int x = createNode();
//if (touch[i][j].size() > 0) {
//for (int k = 0; k < touch[i][j].size(); k++) connect(x, touch[i][j][k]);
if (touch[i][j][0] != -1) connect(x, touch[i][j][0]);
if (touch[i][j][1] != -1) connect(x, touch[i][j][1]);
//}
//touch[i][j].pb(x);
//if (touch[i+1][j].size() > 0) {
//for (int k = 0; k < touch[i+1][j].size(); k++) connect(x, touch[i+1][j][k]);
if (touch[i+1][j][0] != -1) connect(x, touch[i+1][j][0]);
if (touch[i+1][j][1] != -1) connect(x, touch[i+1][j][1]);
//}
//touch[i+1][j].pb(x);
//if (touch[i+2][j].size() > 0) {
//for (int k = 0; k < touch[i+2][j].size(); k++) connect(x, touch[i+2][j][k]);
if (touch[i+2][j][0] != -1) connect(x, touch[i+2][j][0]);
if (touch[i+2][j][1] != -1) connect(x, touch[i+2][j][1]);
//}
//touch[i+2][j].pb(x);
}
}
}
}
int count_component(int x) {
vis[x] = true;
int ret = 1;
for (int i = 0; i < edges[x].size(); i++) {
int y = edges[x][i];
if (vis[y]) continue;
ret += count_component(y);
}
return ret;
}
int es[ARRSIZE] = {0};
int main(int argc, char **argv) {
ios_base::sync_with_stdio(0);
cin.tie(0);
func();
if (N > 2000 && M > 2000) exit(-1);
int sum = 0;
set<ii> S;
for (int i = 0; i < num_nodes; i++) es[i] = edges[i].size();
for (int i = 0; i < num_nodes; i++) S.insert(mp(es[i], i));
while (!S.empty()) {
int x = (*S.begin()).second;
S.erase(S.begin());
for (int i = 0; i < edges[x].size(); i++) {
int y = edges[x][i];
auto it = S.find(mp(es[y], y));
if (it != S.end()) {
S.erase(it);
for (int j = 0; j < edges[y].size(); j++) {
int y2 = edges[y][j];
auto it2 = S.find(mp(es[y2], y2));
if (it2 != S.end()) {
S.erase(it2);
es[y2]--;
S.insert(mp(es[y2], y2));
}
}
}
}
sum++;
}
/*for (int i = 0; i < num_nodes; i++) {
if (vis[i]) continue;
int a = bfs(i, true);
clean(i);
int b = bfs(i, false);
assert(abs(a-b) <= 1);
sum += max(a, b);
}*/
cout << sum << endl;
return 0;
}
