include xpllib; \for Print

char Grid;
int  W, H, Len, Cnt;
int  Next(4), Dir;

proc Walk(Y, X);
int  Y, X;
int  I, T;
[if Y=0 or Y=H or X=0 or X=W then
    [Cnt:= Cnt+2;  return];
T:= Y * (W + 1) + X;
Grid(T):= Grid(T)+1;
Grid(Len-T):= Grid(Len-T)+1;
for I:= 0 to 4-1 do
    if Grid(T + Next(I)) = 0 then
        Walk(Y+Dir(I,0), X+Dir(I,1));
Grid(T):= Grid(T)-1;
Grid(Len-T):= Grid(Len-T)-1;
];

func Solve(HH, WW, Recur);
int HH, WW, Recur;
int T, CX, CY, X;
[H:= HH;  W:= WW;
if H & 1 then [T:= W;  W:= H;  H:= T];
if H & 1 then return 0;
if W = 1 then return 1;
if W = 2 then return H;
if H = 2 then return W;
CY:= H/2;  CX:= W/2;
Len:= (H + 1) * (W + 1);
Grid:= ReallocMem(Grid, Len);
FillMem(Grid, 0, Len);  Len:= Len-1;
Next(0):= -1;
Next(1):= -W - 1;
Next(2):= 1;
Next(3):= W + 1;
if Recur then Cnt:= 0;
for X:= CX+1 to W-1 do
    [T:= CY * (W + 1) + X;
    Grid(T):= 1;
    Grid(Len - T):= 1;
    Walk(CY - 1, X);
    ];
Cnt:= Cnt+1;
if H = W then Cnt:= Cnt * 2
else if (W&1) = 0 and Recur then Solve(W, H, 0);
return Cnt;
];

int Y, X;
[Grid:= 0;
Dir:= [[0, -1], [-1, 0], [0, 1], [1, 0]];
for Y:= 1 to 10 do
    for X:= 1 to Y do
        if (X&1) = 0 or (Y&1) = 0 then
            Print("%d x %d: %d\n", Y, X, Solve(Y, X, 1));
]