hdu 1788

#include <cstdio>
#include <cstring>
#include <iostream>
#include <stack>
#include <queue>
#include <map>
#include <algorithm>
#include <vector>

using namespace std;

const int maxn = 1000005;

typedef long long LL;

LL gcd( LL a,LL b)
{
if(b == 0) return a;
else  return gcd(b,a%b);
}
int main()
{
LL i,n,a1,aa,r1,a2,r2,ans,a,b,c,d,x0,y0,lcm;
while(scanf("%lld%lld",&n,&aa)!=EOF){
bool flag = 1;
if(n == 0 && aa==0) break;
lcm = 1;
for(int i=0;i<n;i++){
cin>>a;
lcm = (lcm*a)/gcd(lcm,a);
}
printf("%lld\n",lcm-aa);
}
return 0;
}