var grid: int[16];
var q: int[64];

fun main()
{
    var y = 0;
    do
    {
        var row = 0;
        var x = 0;
        do
        {
            var val = getInt();
            row |= val << (x << 2);
            drawData(val * 7);
            x++;
        } while (x < 16);
        row |= row << 1;
        grid[y] = row;
        y++;
    } while (y < 16);

    var rx = getInt();
    var ry = getInt();
    var rcoord = (ry << 4) + rx;
    drawAddr(rcoord);
    drawData(10);
    drawSwap(1);

    while (true)
    {
        var fx = getInt();
        var fy = getInt();
        var fcoord = (fy << 4) + fx;
        drawAddr(fcoord);
        drawData(9);

        q[0] = fcoord;
        grid[fy] |= 2 << (fx << 2);
        var qStart = 0;
        var qSize = 1;

        do
        {
            var qEnd = qSize;

            for (var qIdx = qStart; qIdx != qEnd; qIdx = (qIdx + 1) & 63)
            {
                var coord = q[qIdx];
                var ncoord = coord + 16;
                var ny = ncoord >> 4;
                var nx = ncoord & 15;
                var bits = grid[ny] >> (nx << 2);
                if ((bits & 2) == 0)
                {
                    //drawAddr(ncoord);
                    //drawData(3);
                    //drawSwap(1);
                    q[qSize] = ncoord;
                    qSize = (qSize + 1) & 63;
                    grid[ny] |= 2 << (nx << 2);
                }
            }

            for (var qIdx = qStart; qIdx != qEnd; qIdx = (qIdx + 1) & 63)
            {
                var coord = q[qIdx];
                var ncoord = coord - 1;
                var ny = ncoord >> 4;
                var nx = ncoord & 15;
                var bits = grid[ny] >> (nx << 2);
                if ((bits & 2) == 0)
                {
                    //drawAddr(ncoord);
                    //drawData(3);
                    //drawSwap(1);
                    q[qSize] = ncoord;
                    qSize = (qSize + 1) & 63;
                    grid[ny] |= 6 << (nx << 2);
                }
            }

            for (var qIdx = qStart; qIdx != qEnd; qIdx = (qIdx + 1) & 63)
            {
                var coord = q[qIdx];
                var ncoord = coord - 16;
                var ny = ncoord >> 4;
                var nx = ncoord & 15;
                var bits = grid[ny] >> (nx << 2);
                if ((bits & 2) == 0)
                {
                    //drawAddr(ncoord);
                    //drawData(3);
                    //drawSwap(1);
                    q[qSize] = ncoord;
                    qSize = (qSize + 1) & 63;
                    grid[ny] |= 10 << (nx << 2);
                }
            }

            for (var qIdx = qStart; qIdx != qEnd; qIdx = (qIdx + 1) & 63)
            {
                var coord = q[qIdx];
                var ncoord = coord + 1;
                var ny = ncoord >> 4;
                var nx = ncoord & 15;
                var bits = grid[ny] >> (nx << 2);
                if ((bits & 2) == 0)
                {
                    //drawAddr(ncoord);
                    //drawData(3);
                    //drawSwap(1);
                    q[qSize] = ncoord;
                    qSize = (qSize + 1) & 63;
                    grid[ny] |= 14 << (nx << 2);
                }
            }

            if (((grid[ry] >> (rx << 2)) & 2) != 0)
            {
                break;
            }

            qStart = qEnd;
        } while (qStart != qSize);

        do
        {
            drawAddr(rcoord);
            drawData(0);

            var bits = (grid[ry] >> (rx << 2)) & 12;

            if (bits == 0) rcoord -= 16;
            else if (bits == 4) rcoord += 1;
            else if (bits == 8) rcoord += 16;
            else rcoord -= 1;
            ry = rcoord >> 4;
            rx = rcoord & 15;

            drawAddr(rcoord);
            drawData(10);
            drawSwap(1);
        } while (rcoord != fcoord);

        var y = 0;
        do
        {
            var row = grid[y];
            row &= 0x1111111111111111;
            row |= row << 1;
            grid[y] = row;
            y++;
        } while (y < 16);
    }
}