It is known that the positive integer n is a common multiple of 7 and 8, and the digits of each digit of n are all 7 or 8, and there is at least one digit 7 and 8 respectively. Then what is the minimum value of n that satisfies the above conditions.
已知正整数n是7与8的公倍数，n各位上的数码全都是7或8，且数码7与8各至少有一个．则满足上述条件的最小n的值为多少．
<result>7_888_888</result>