#include<bits/stdc++.h> #define int long long using namespace std; inline int read(){ int x=0,f=0;char c=getchar(); while(c<48||c>57)f|=(!(c^'-')),c=getchar(); while(c>=48&&c<=57)x=(x<<1)+(x<<3)+(c^48),c=getchar(); return f?-x:x; } int n,a[200005]; signed main(){ n=read(); for(int i=1;i<=n;i++)a[i]=read(); cout<<(n>>1)*1099509530625ll<<endl; return 0; }