#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pii> vpii;
typedef vector<pll> vpll;
typedef vector<string> vs;
typedef vector<vb> vvb;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
#define all(x) x.begin(), x.end()
#define rep(i,a,b) for(int i = a; i < b; i++)
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int N, M;
cin >> N;
cin >> M;
vector<string> board(N);
rep(n,0,N) cin >> board[n];
vi Ns(N*M);
vi Ms(N*M);
int i = 0;
rep(dist,0,N+M) {
for(int m = max(0,dist-N+1); m <= min(dist,M-1); m++, i++) {
int n = dist-m;
Ns[i] = n;
Ms[i] = m;
}
}
vi best(N*M*3);
for(i = 0; i < N*M; i++) {
int n = Ns[i];
int m = Ms[i];
if(i > 0) {
best[i] = best[i-1];
best[i+N*M] = best[i-1];
best[i+2*N*M] = max(best[i-1+N*M], best[i-1+2*N*M]);
if(m == 0 || n == N-1) best[i+2*N*M] = max(best[i+2*N*M], best[i-1]);
}
if(n+2 < N && board[n][m] == 'R' && board[n+1][m] == 'G' && board[n+2][m] == 'W') { // vertical
if(i == 0) best[i] = best[i+N*M] = best[i+2*N*M] = 1;
if(i-1 >= 0 && (m == 0 || n == N-1)) best[i+2*N*M] = best[i-1]+1;
if(i-1 >= 0 && m-1 >= 0 && n+1 < N) best[i+2*N*M] = max(best[i+2*N*M], best[i-1+2*N*M]+1);
if(i-2 >= 0 && m-2 >= 0 && n+2 < N) best[i+2*N*M] = max(best[i+2*N*M], best[i-2+N*M]+1);
if(i-3 >= 0 && m-3 >= 0 && n+3 < N) best[i+2*N*M] = max(best[i+2*N*M], best[i-3]+1);
}
if(m+2 < M && board[n][m] == 'R' && board[n][m+1] == 'G' && board[n][m+2] == 'W') { // horizontal
if(i == 0) best[i] = 1;
else if(m-0 >= 0 && n+0 < N) best[i] = max(best[i], best[i-1]+1);
}
best[i+N*M] = max(best[i+N*M], best[i+2*N*M]);
best[i] = max(best[i], best[i+N*M]);
}
cout << best[N*M-1] << '\n';
}
