code CrLf=9, IntOut=11, Text=12;
int  N, D, Best(16);

proc TrySwaps(A, F, S);
int  A, F, S;
int  B(16), I, J, K;
[if D > Best(N) then Best(N):= D;
loop    [if A(S)=-1 ! A(S)=S then quit;
        if D+Best(S) <= Best(N) then return;
        if S = 0 then quit;
        S:= S-1;
        ];
D:= D+1;
for I:= 0 to S do B(I):= A(I);
K:= 1;
for I:= 1 to S do
        [K:= K<<1;
        if B(I)=-1 & (F&K)=0 ! B(I)=I then
                [J:= I;  B(0):= J;
                while J do [J:= J-1;  B(I-J):= A(J)];
                TrySwaps(B, F!K, S);
                ];
        ];
D:= D-1;
];

int  I, X(16);
[for I:= 0 to 16-1 do
        [X(I):= -1;  Best(I):= 0];
X(0):= 0;
for N:= 1 to 13 do
        [D:= 0;
        TrySwaps(X, 1, N-1);
        IntOut(0, N);  Text(0, ": ");  IntOut(0, Best(N));  CrLf(0);
        ];
]