#include<bits/stdc++.h>
int N,p[200001];
int main(){
int x,y;
scanf("%d%d",&x,&y);
N=x;
if(y*2+1>N)puts("Impossible");
else{
printf("%d\\n",N);
for(int i=1;i<=(N+1)/2;i++)printf("%d ",y);
for(int i=(N+1)/2+1;i<=N;i++)printf("%d%c",y+1," \\n"[i==N]);
}
return 0;
}