#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));
vector <vi> b(N, vi(N, 3));
map<int, int> mp;
void solve() {
cin>>n>>m;
int k=1;
for(int i=1; i<=n; i++){
for(int j=1; j<=m; j++){
b[i][j]=k;
k++;
char c;
cin>>c;
if(c=='R'){
a[i][j]=0;
}
else if(c=='G'){
a[i][j]=1;
}
else{
a[i][j]=2;
}
}
}
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[b[i][j]]++;
mp[b[i][j+1]]++;
mp[b[i][j+2]]++;
}
}
}
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[b[i][j]]++;
mp[b[i+1][j]]++;
mp[b[i+2][j]]++;
}
}
}
priority_queue <pair<int, tuple<int, int, int>>> q;
for(int i=1; i<=n; i++){
for(int j=1; j<=m; j++){
if(a[i][j]==0 and a[i][j+1]==1 and a[i][j+2]==2){
int temp = 1 + mp[b[i][j]]-1 + mp[b[i][j+1]]-1 + mp[b[i][j+2]]-1;
q.push({temp, make_tuple(b[i][j], b[i][j+1], b[i][j+2])});
}
}
}
for(int i=1; i<=n; 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[b[i][j]]-1 + mp[b[i+1][j]]-1 + mp[b[i+2][j]]-1;
q.push({temp, make_tuple(b[i][j], b[i+1][j], b[i+2][j])});
}
}
}
int ans=0;
while(!q.empty()){
pair<int, tuple<int, int, int>> top_element = q.top();
int mx = top_element.first;
if(mx==1) break;
q.pop();
int second_tuple_first = get<0>(top_element.second);
int second_tuple_second = get<1>(top_element.second);
int second_tuple_third = get<2>(top_element.second);
int temp = 1 + mp[second_tuple_first]-1 + mp[second_tuple_second]-1 + mp[second_tuple_third]-1;
if(temp != mx){
q.push({temp, top_element.second});
continue;
}
mp[second_tuple_first]--;
mp[second_tuple_second]--;
mp[second_tuple_third]--;
}
cout<<q.size();
}
signed main() {
fast_io;
int tc = 1;
// scanf("%d", &tc);
while (tc--)
solve();
}
