#include<bits/stdc++.h>
using namespace std;
string s[3010];
int dp[3010][3010];
int main(){
int n,m;
cin>>n>>m;
for(int i=1;i<=n;i++){
cin>>s[i];
}
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++){
dp[i][j]=dp[i][j-1]+dp[i-1][j]-dp[i-1][j-1];
if(i>=3){
if((s[i][j-1]=='W'&&s[i-1][j-1]=='G')&&s[i-2][j-1]=='R'){
dp[i][j]=max(dp[i][j],dp[i][j-1]+dp[i-3][j]-dp[i-3][j-1]+1);
}
}
if(j>=3){
if((s[i][j-1]=='W'&&s[i][j-2]=='G')&&s[i][j-3]=='R'){
dp[i][j]=max(dp[i][j],dp[i-1][j]+dp[i][j-3]-dp[i-1][j-3]+1);
}
}
}
}
cout<<dp[n][m];
}
