#include<bits/stdc++.h>
using namespace std;
const int MAXN=1e7+15;
const int INF=1e9;
vector<int> ds[MAXN];
int lay[MAXN],px[MAXN],py[MAXN],cnt[MAXN];
string s[3333];
bool bfs(int n)
{
queue<int> Q;
for(int i=1;i<=n;i++) if(!px[i]) Q.push(i),lay[i]=0;
else lay[i]=1e9;
bool f=false;
while(!Q.empty())
{
int a=Q.front();
Q.pop();
for(auto v:ds[a]) if(px[a]!=v)
{
if(!py[v]) f=true;
else if(lay[py[v]]==1e9) lay[py[v]]=lay[a]+1,Q.push(py[v]);
}
}
return f;
}
bool dfs(int s)
{
for(int& i=cnt[s];i+1;i--)
{
int v=ds[s][i];
if(px[s]!=v) if(!py[v]||(lay[py[v]]==lay[s]+1&&dfs(py[v])))
{
if(px[s]) py[px[s]]=0;
px[s]=v,py[v]=s;
return true;
}
}
return false;
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n,m,sum=0;
cin>>n>>m;
for(int i=1;i<=n;i++)
{
cin>>s[i];
s[i]=' '+s[i];
}
for(int i=1;i<=n-2;i++)
{
for(int j=1;j<=m;j++) if(s[i][j]=='R'&&s[i+1][j]=='G'&&s[i+2][j]=='W')
{
if(j+1<m&&s[i][j]=='R'&&s[i][j+1]=='G'&&s[i][j+2]=='W') ds[(i-1)*m+j].push_back((i-1)*m+j);
if(j>1&&j<m&&s[i+1][j-1]=='R'&&s[i+1][j]=='G'&&s[i+1][j+1]=='W') ds[(i-1)*m+j].push_back(i*m+j-1);
if(j>2&&s[i+2][j-2]=='R'&&s[i+2][j-1]=='G'&&s[i+2][j]=='W') ds[(i-1)*m+j].push_back((i+1)*m+j-2);
sum++;
}
}
for(int i=1;i<=n;i++) for(int j=1;j<=m-2;j++) if(s[i][j]=='R'&&s[i][j+1]=='G'&&s[i][j+2]=='W') sum++;
int ans=0;
while(bfs(n))
{
for(int i=1;i<=n;i++) cnt[i]=ds[i].size()-1;
for(int i=1;i<=n;i++) if(!px[i]) ans+=dfs(i);
}
cout<<sum-ans;
}
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