INT(4, 250000, n) SPACE INT(1, 500000, m) SPACE INT(1, n-1, c1) SPACE INT(1, n-1, c2) NEWLINE
ASSERT(n % 2 == 0)
ASSERT(c1 % 2 == 1)
ASSERT(c2 % 2 == 1)
ASSERT(c1 < c2)

REPI(i, m)
   INT(1, n, a[i]) SPACE INT(1, n, b[i])
   ASSERT(a[i] != b[i])
   IF (a[i] % 2 != b[i] % 2)
      SPACE INT(1, n, c) NEWLINE
      ASSERT(c == c1 || c == c2)
   ELSE
      NEWLINE
   END
   IF (a[i] > b[i])
      SET(tmp = a[i])
      SET(a[i] = b[i])
      SET(b[i] = tmp)
   END
END

ASSERT(UNIQUE(a, b))