#include <bits/stdc++.h> using namespace std; typedef signed long long ll; #undef _P #define _P(...) (void)printf(__VA_ARGS__) #define FOR(x,to) for(x=0;x<(to);x++) #define FORR(x,arr) for(auto& x:arr) #define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++) #define ALL(a) (a.begin()),(a.end()) #define ZERO(a) memset(a,0,sizeof(a)) #define MINUS(a) memset(a,0xff,sizeof(a)) //------------------------------------------------------- int N; ll A[202020]; ll dp[202020][40]; void solve() { int i,j,k,l,r,x,y; string s; cin>>N; FOR(i,N) cin>>A[i+1]; for(i=N;i>=1;i--) { for(j=-18;j<=18;j++) { dp[i][j+20]=max({dp[2*i][j+20+1]+dp[2*i+1][j+20-1],dp[2*i][j+20-1]+dp[2*i+1][j+20+1],dp[2*i][j+20+1],dp[2*i+1][j+20+1]})+j*A[i]; } } cout<<dp[1][20]<<endl; } int main(int argc,char** argv){ string s;int i; if(argc==1) ios::sync_with_stdio(false), cin.tie(0); FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin); cout.tie(0); solve(); return 0; }