# This does not check positions of cars; need another program for that

# Two positive integers bounded by 250:
INT(1,250,m) SPACE INT(1,250,n) NEWLINE

SET(onecount=0,twocount=0)
REPI(i,m)
  REPI(j,n, SPACE) # this means space-separated items, but not trailing
    INT(-2,2^31-1,x) # any non-negative integer value (32-bit)
    SET(grid[i,j] = x)
    IF (x == -1)
      SET(onecount=onecount+1)
    ELSE 
      IF(x == -2)
        SET(twocount=twocount+1)
      END
    END
  END
  NEWLINE
END

# Make sure there are an even number of filled slots since each car uses 2:
SET(k = m*n - onecount - twocount)
ASSERT(k % 2 == 0)

# Exactly one empty space:
ASSERT(onecount == 1)

# Row, col of goal cell must be within the bounds:
INT(1,m,x) SPACE INT(1,n,y) NEWLINE  

# Goal cell should not be empty or blocked:
ASSERT(grid[x-1,y-1] != -1)
ASSERT(grid[x-1,y-1] != -2)