#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;
template<typename T> using ordered_set = tree<T,null_type,less_equal<T>,rb_tree_tag,
tree_order_statistics_node_update>;
#define ll long long
#define pi pair<int,int>
#define vi vector<int>
#define pb push_back
#define all(a) a.begin(),a.end()
void solve(){
int n,m; cin >> n >> m;
int cnt = 0;
vector<vector<char>> grid(n,vector<char>(m));
for(int i = 0; i < n; i++)
for(int j = 0; j < m; j++)
cin >> grid[i][j];
vector<char> last(n,'B');
int ans = 0;
for(int j = m-1; j >= 0; j--){
for(int i = 0; i < n-2; i++){
if(grid[i][j]=='R' && grid[i+1][j]=='G' && grid[i+2][j]=='W')
grid[i][j] = grid[i+1][j] = grid[i+2][j] = 'B', ans++;
}
for(int i = 0; i < n && j < m-2; i++){
if(grid[i][j]=='R' && grid[i][j+1]=='G' && grid[i][j+2]=='W')
grid[i][j] = grid[i][j+1] = grid[i][j+2] = 'B', ans++;
}
}
cout << ans;
}
signed main(){
cin.tie(0)->sync_with_stdio(0);
int t = 1;
while(t--) solve();
}
