View Compilation Error

0_0_26427560_24856.cpp: In function 'void bfs(int, int, int, int)':
0_0_26427560_24856.cpp:32:9: error: no match for 'operator[]' (operand types are 'node' and 'int')
    if((a[nx][ny]==0||a[nx][ny]==a[x2][y2])&&vis[nx][ny]==0&&nx<=n&&nx>=1&&ny<=m&&ny>=1)
         ^
0_0_26427560_24856.cpp:32:23: error: no match for 'operator[]' (operand types are 'node' and 'int')
    if((a[nx][ny]==0||a[nx][ny]==a[x2][y2])&&vis[nx][ny]==0&&nx<=n&&nx>=1&&ny<=m&&ny>=1)
                       ^
0_0_26427560_24856.cpp:32:34: error: no match for 'operator[]' (operand types are 'node' and 'int')
    if((a[nx][ny]==0||a[nx][ny]==a[x2][y2])&&vis[nx][ny]==0&&nx<=n&&nx>=1&&ny<=m&&ny>=1)
                                  ^