#include <bits/stdc++.h>
using namespace std;
string grid[3000];
int dp[3002][3002][3], prv = 0;
int main() {
cin.tie(0)->sync_with_stdio(0);
int n, m;
cin >> n >> m;
for (int i = 0; i < n; i++) cin >> grid[i];
for (int diag = 2; diag <= n + m - 2; diag++) {
for (int i = 0; i < n; i++) {
int j = diag - i;
if (j < 0 || j >= m) continue;
dp[i][j][0] = prv;
if (j > 1 && grid[i][j] == 'W' && grid[i][j - 1] == 'G' && grid[i][j - 2] == 'R')
dp[i][j][1] = prv + 1;
if (i > 1 && grid[i][j] == 'W' && grid[i - 1][j] == 'G' && grid[i - 2][j] == 'R') {
if (j == m - 1) dp[i][j][2] = prv + 1;
else if (j == m - 2) dp[i][j][2] = max(dp[i - 1][j + 1][2], dp[i - 1][j + 1][0]) + 1;
else dp[i][j][2] = max({dp[i - 1][j + 1][2], dp[i - 2][j + 2][2], dp[i - 2][j + 2][0]}) + 1;
}
prv = *max_element(dp[i][j], dp[i][j] + 3);
}
}
cout << prv;
return 0;
}
