/*input
3 4
RGWR
GRGG
RGWW
*/
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef tree<int,null_type,less_equal<int>,rb_tree_tag,tree_order_statistics_node_update> indexed_set;
//order_of_key #of elements less than x
// find_by_order kth element
using ll=long long;
using ld=double;
using pii=pair<int,int>;
#define f first
#define s second
#define pb push_back
#define REP(i,n) for(int i=0;i<n;i++)
#define REP1(i,n) for(int i=1;i<=n;i++)
#define FILL(n,x) memset(n,x,sizeof(n))
#define ALL(_a) _a.begin(),_a.end()
#define sz(x) (int)x.size()
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()),c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
const ll INF64=1e18+1;
const int INF=0x3f3f3f3f;
const int MOD=1e9+7;
const ld PI=acos(-1);
const ld eps=1e-6;
#define lowb(x) x&(-x)
#define MNTO(x,y) x=min(x,(__typeof__(x))y)
#define MXTO(x,y) x=max(x,(__typeof__(x))y)
inline ll mult(ll a,ll b){
if(a>=MOD) a%=MOD;
if(b>=MOD) b%=MOD;
return (a*b)%MOD;
}
inline ll mypow(ll a,ll b){
if(b<=0) return 1;
ll res=1LL;
while(b){
if(b&1) res=mult(res,a);
a=mult(a,a);
b>>=1;
}
return res;
}
const int maxn=4e3+7;
const int maxlg=__lg(maxn)+2;
string arr[maxn];
string ans="RGW";
int dp[maxn][maxn][2];
bool ok(int o,int i,int j){
string a="";
if(o) REP(k,3) a.pb(arr[i][j+k-1]);
else REP(k,3) a.pb(arr[i+k-1][j]);
return (a==ans);
}
int32_t main(){
ios::sync_with_stdio(false),cin.tie(0);
int n,m;
cin>>n>>m;
REP1(i,n){
cin>>arr[i];
arr[i]='0'+arr[i];
arr[i].pb('0');
}
REP(i,n+1) REP(j,m+1) REP(a,2) dp[i][j][a]=-INF;
int ans=0;
for(int i=2;i<=n+m;i++){
int mx=0;
int X=-1,Y=-1;
for(int x=max(1,i-m);x<=min(n,i-1);x++){
int y=i-x;
REP(a,2){
if(ok(a,x,y)){
dp[x][y][a]=max(mx,dp[x-1][y+1][a])+1;
}
}
REP(a,2) MXTO(mx,dp[x-1][y+1][a]);
X=x,Y=y;
}
REP(a,2) MXTO(mx,dp[X][Y][a]);
ans+=mx;
}
cout<<ans<<'\n';
}
