#include <bits/stdc++.h>
using namespace std;
int N, M;
char arr[3005][3005];
int dp[3][3005][3005]; //0 ntg, 1 hor, 2 ver
int main(){
cin.sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> N >> M;
for(int i = 1; i<=N; i++){
for(int j = 1; j<=M; j++){
cin >> arr[i][j];
}
}
int lst = 0, pre = 0;
for(int d = 2; d<=N+M; d++){
for(int r = 1; r<=N; r++){
int c = d-r;
if(c <= 0 || c > M){
continue;
}
dp[0][r][c] = max({lst, dp[0][r-1][c+1], dp[1][r-1][c+1], dp[2][r-1][c+1]});
if(arr[r][c] == 'G' && arr[r][c-1] == 'R' && arr[r][c+1] == 'W'){
dp[1][r][c] = max({dp[0][r-1][c+1], dp[1][r-1][c+1], pre}) + 1;
}
if(arr[r][c] == 'G' && arr[r-1][c] == 'R' && arr[r+1][c] == 'W'){
dp[2][r][c] = max({dp[0][r-1][c+1], dp[2][r-1][c+1], pre}) + 1;
}
lst = max({dp[0][r][c], dp[1][r][c], dp[2][r][c]});
}
pre = lst;
}
cout << pre << "\n";
}
