// #pragma optimize ("g",on)
// #pragma GCC optimize ("inline")
// #pragma GCC optimize ("Ofast")
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC optimize ("03")
#include <bits/stdc++.h>
#define pb push_back
#define SS ios_base::sync_with_stdio(0);cin.tie(nullptr);cout.tie(nullptr);
// #define int long long
#define all(v) v.begin(),v.end()
using namespace std;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
const int N = 3077, inf = 1e9, mod = 998244353;
vector<int> g[N][N];
pair<int, int> was[N][N];
int used[N][N], timer;
bool dfs(int x, int y){
if(used[x][y] == timer) return false;
used[x][y] = timer;
for(int t : g[x][y]){
if(t == 1){
bool ch = 0;
for(int i = y; i <= y + 2; i++){
if(was[x][i].first > 0 && !dfs(was[x][i].first, was[x][i].second)){
ch = 1;
break;
}
}
if(!ch){
for(int i = y; i <= y + 2; i++){
was[x][i] = {x, y};
}
return true;
}
}
if(t == 2){
bool ch = 0;
for(int i = x; i <= x + 2; i++){
if(was[i][y].first > 0 && !dfs(was[i][y].first, was[i][y].second)){
ch = 1;
break;
}
}
if(!ch){
for(int i = x; i <= x + 2; i++){
was[i][y] = {x, y};
}
return true;
}
}
}
return false;
}
void solve(){
int n, m;
cin >> n >> m;
int a[n + 1][m + 1], ok[n + 1][m + 1] = {}, dp[n + 1][3] = {};
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;
if(c == 'G') a[i][j] = 1;
if(c == 'W') a[i][j] = 2;
}
}
for(int i = 1; i <= n; i++){
for(int j = 1; j <= m; j++){
if(j + 2 <= m && a[i][j] == 0 && a[i][j + 1] == 1 && a[i][j + 2] == 2){
ok[i][j] ^= 1;
}
if(i + 2 <= n && a[i][j] == 0 && a[i + 1][j] == 1 && a[i + 2][j] == 2){
ok[i][j] ^= 2;
}
}
}
int ans = 0;
for(int sum = 2; sum <= n + m; sum++){
bool re = 0;
int res = 0;
for(int i = 1; i <= n; i++){
if(sum - i < 1 || sum - i > m) continue;
if(!re){
dp[i][0] = dp[i][1] = dp[i][2] = 0;
if((ok[i][sum - i] & 1)) dp[i][1] = 1;
if((ok[i][sum - i] & 2)) dp[i][2] = 1;
res = max(dp[i][1], dp[i][2]);
re = 1;
continue;
}
dp[i][0] = max({dp[i - 1][0], dp[i - 1][1], dp[i - 1][2]});
dp[i][1] = dp[i][2] = 0;
if((ok[i][sum - i] & 1)){
dp[i][1] = 1;
int mx = 0;
if(i > 1) mx = max(mx, dp[i - 1][1]);
if(i > 2) mx = max({mx, dp[i - 2][0], dp[i - 2][1]});
dp[i][1] += mx;
}
if((ok[i][sum - i] & 2)){
dp[i][2] = 1;
if(i > 1) dp[i][2] += max({dp[i - 1][0], dp[i - 1][1], dp[i - 1][2]});
}
res = max({res, dp[i][0], dp[i][1], dp[i][2]});
}
ans += res;
}
cout << ans;
}
signed main(){
SS
// freopen("trains.in", "r", stdin);
// freopen("trains.out", "w", stdout);
int t = 1;
// cin >> t;
while(t--){
solve();
}
}
