include<bits/stdc++.h>

using namespace std; int n[10000],a; void ba(int c){

int s;
cin>>s;
n[c]=s;
if(s==-1){
	return;
}
ba(c*2);
ba(c*2+1);

} void baa(int c,int sum){

if(n[c]!=-1){
	sum+=n[c];
}
if(n[c]==-1){
	return;
}
if(n[c*2]==-1&&n[c*2+1]==-1){
	a+=sum;
	return;
}
baa(c*2,sum*10);
baa(c*2+1,sum*10);

} int main(){

ba(1);
baa(1,0);
cout<<a;
return 0;

}