#include <iostream>
using namespace std;
long long dpV[3000][3000];
long long dpH[3000][3000];
char grid[3000][3000];
long long N, M;
bool vert(long long i, long long j)
{
if(i == 0 || i == N-1) return 0;
if(grid[i-1][j] != 'R') return 0;
if(grid[i][j] != 'G') return 0;
if(grid[i+1][j] != 'W') return 0;
return 1;
}
bool horiz(long long i, long long j)
{
if(j == 0 || j == M-1) return 0;
if(grid[i][j-1] != 'R') return 0;
if(grid[i][j] != 'G') return 0;
if(grid[i][j+1] != 'W') return 0;
return 1;
}
long long main()
{
cin >> N >> M;
for(long long i = 0; i < N; i++) for(long long j = 0; j < M; j++) cin >> grid[i][j];
long long res = 0;
for(long long I = 0; I < N; I++)
{
dpH[I][0] = 0;
dpV[I][0] = vert(I, 0);
for(long long s = 0; I-s >= 0 && s < M; s++)
{
long long i = I-s;
long long j = s;
dpH[i][j] = max(dpH[i+1][j-1], dpV[i+1][j-1]);
dpH[i][j] = max(dpH[i][j], dpH[i+1][j-1] + horiz(i, j));
dpV[i][j] = max(dpH[i+1][j-1], dpV[i+1][j-1]);
dpV[i][j] = max(dpV[i][j], dpV[i+1][j-1] + vert(i, j));
}
}
for(long long J = 0; J < M; J++)
{
dpV[N-1][J] = 0;
dpH[N-1][J] = horiz(N-1, J);
for(long long s = 0; N-1-s >= 0 && J+s < M; s++)
{
long long i = N-1-s;
long long j = J+s;
dpH[i][j] = max(dpH[i+1][j-1], dpV[i+1][j-1]);
dpH[i][j] = max(dpH[i][j], dpH[i+1][j-1] + horiz(i, j));
dpV[i][j] = max(dpH[i+1][j-1], dpV[i+1][j-1]);
dpV[i][j] = max(dpV[i][j], dpV[i+1][j-1] + vert(i, j));
}
}
for(long long j = 0; j < M; j++) res += max(dpV[0][j], dpH[0][j]);
for(long long i = 1; i < N; i++) res += max(dpV[i][M-1], dpH[i][M-1]);
cout << res << '\n';
}
Compilation message
cc1plus: error: '::main' must return 'int'
