#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int grid[3003][3003];
int dp[3003][3003][3];
int main()
{
int n, m;
cin >> n >> m;
for(int i = 0; i <=3002; i ++)
{
for(int j = 0; j <= 3002;j++)
{
grid[i][j] = -1;
dp[i][j][0] = dp[i][j][1] = dp[i][j][2] = 0;
}
}
for(int i = 1; i <=n; i ++)
{
for(int j = 1; j <=m; j ++)
{
char t;
cin >> t;
if(t == 'R')
{
grid[i][j] = 0;
}
else
{
t == 'G' ? grid[i][j] = 1 : grid[i][j] = 2;
}
//cout << grid[i][j];
}//cout << '\n';
}
for(int i = 2; i <= (n + m); i ++)
{
for(int j = max(i-n, 1); j <= min(i - 1, m); j ++)
{
//cout << grid[i-j][j];
//we loop at dp[i - j][j][ 0 == vertical, 1 = horiz, 2 = no dango]
// if we don't make a dango with this block
dp[i-j][j][2] = max(max(dp[i-j + 1][j - 1][0], dp[i-j + 1][j - 1][1]) , dp[i-j + 1][j - 1][2]);
//cout << " dp[2] : " << dp[i-j][j][2] << '\n';
if(grid[i-j][j] == 1)
{
if(grid[i-j-1][j] == 0 && grid[i-j+1][j] == 2)
{
dp[i-j][j][0] = max(dp[i-j + 1][j-1][0], dp[i-j + 1][j-1][2]) + 1;
//cout << " dp[0] : " << dp[i-j][j][0] << '\n';
}
if(grid[i-j][j-1] == 0 && grid[i-j][j + 1] == 2)
{
dp[i-j][j][1] = max(dp[i-j + 1][j-1][1], dp[i-j + 1][j-1][2]) + 1;
//cout << " dp[1] : " << dp[i-j][j][1] << '\n';
}
}
} //cout << '\n';
}
ll ans = 0;
for(int i = 1; i <=m; i ++)
{
ans += max(max(dp[1][i][0], dp[1][i][1]) , dp[1][i][2]);
}
for(int i = 2; i <=n; i ++)
{
ans += max(max(dp[i][m][0], dp[i][m][1]) , dp[i][m][2]);
}
cout << ans;
}
