#include<bits/stdc++.h>
using namespace std;
#define int long long
#define ff first
#define ss second
#define pb push_back
const int N=6e5+5;
int dp[N][2];
signed main(){
int n,k;
cin>>n>>k;
for(int i=1;i<n;i++){
int a,b;
cin>>a>>b;
}
vector<int>v(k+1);
for(int i=1;i<=k;i++)cin>>v[i];
sort(v.begin(),v.end());
for(int i=1;i<=n;i++){
dp[i][0]=1e9;
dp[i][1]=1e9;
}
dp[1][1]=1;
for(int i=2;i<=k;i++){
dp[i][1]=min(dp[i-1][0],dp[i-1][1])+1;
if((v[i]-v[i+1])%2==0){
dp[i][0]=dp[i-1][1];
}
}
cout<<min(dp[k][1],dp[k][0])<<endl;;
int t=0;
for(int i=2;i<=k;i++){
if((v[i]-v[i+1])%2==0){
cout<<v[i]+v[i-1]/2<< " ";
t++;
i++;
}
else{
cout<<v[i-1]<<" ";
t++;
}
}
if(t!=min(dp[k][1],dp[k][0]))cout<<v[k];
}
