#include<bits/stdc++.h>
#define en "\n"
#define s second
#define f first
#define fast_io ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define vi vector<int>
#define vii vector<pair<int,int>>
// #define int long long
#define rall(x) x.rbegin(), x.rend()
#define pb push_back
#define loop(a) for(int i = 0; i < a; i++)
#define loopv(i,a) for (int i = 0; i < a; i++)
#define all(x) (x).begin(), (x).end()
#define prDouble(x) printf("%.8f", x)
#define goog(tno) printf("Case #%d: ", tno)
using namespace std;
const int N = 3010;
int n, m;
vector <vi> a(N, vi(N, 3));
map<pair<int, int>, int> mp;
void solve() {
cin>>n>>m;
for(int i=1; i<=n; i++){
for(int j=1; j<=m; j++){
char c;
cin>>c;
if(c=='R'){
a[i][j]=0;
}
else if(c=='G'){
a[i][j]=1;
}
else{
a[i][j]=2;
}
}
}
// Horizontal checks
for(int i=1; i<=n; i++){
for(int j=1; j<=m-2; j++){
if(a[i][j]==0 and a[i][j+1]==1 and a[i][j+2]==2){
mp[{i,j}]++;
mp[{i,j+1}]++;
mp[{i,j+2}]++;
}
}
}
// Vertical checks
for(int i=1; i<=n-2; i++){
for(int j=1; j<=m; j++){
if(a[i][j]==0 and a[i+1][j]==1 and a[i+2][j]==2){
mp[{i,j}]++;
mp[{i+1,j}]++;
mp[{i+2,j}]++;
}
}
}
priority_queue <pair<int, tuple<pair<int,int>, pair<int,int>, pair<int,int>>>> q;
// Horizontal checks for queue insertion
for(int i=1; i<=n; i++){
for(int j=1; j<=m-2; j++){
if(a[i][j]==0 and a[i][j+1]==1 and a[i][j+2]==2){
int temp = 1 + mp[{i,j}]-1 + mp[{i,j+1}]-1 + mp[{i,j+2}]-1;
q.push({temp, make_tuple(make_pair(i,j), make_pair(i,j+1), make_pair(i,j+2))});
}
}
}
// Vertical checks for queue insertion
for(int i=1; i<=n-2; i++){
for(int j=1; j<=m; j++){
if(a[i][j]==0 and a[i+1][j]==1 and a[i+2][j]==2){
int temp = 1 + mp[{i,j}]-1 + mp[{i+1,j}]-1 + mp[{i+2,j}]-1;
q.push({temp, make_tuple(make_pair(i,j), make_pair(i+1,j), make_pair(i+2,j))});
}
}
}
int ans=0;
while(!q.empty()){
auto top_element = q.top();
int mx = top_element.first;
if(mx==1) break;
q.pop();
pair<int, int> first_tuple = get<0>(top_element.second);
pair<int, int> second_tuple = get<1>(top_element.second);
pair<int, int> third_tuple = get<2>(top_element.second);
int temp = 1 + mp[first_tuple]-1 + mp[second_tuple]-1 + mp[third_tuple]-1;
if(temp != mx){
q.push({temp, top_element.second});
continue;
}
mp[first_tuple]--;
mp[second_tuple]--;
mp[third_tuple]--;
}
cout<<q.size();
}
signed main() {
fast_io;
int tc = 1;
while (tc--)
solve();
}
