#include #define ll long long #define int long long #define ss string #define pb push_back #define rev(i,n) for(ll i=0;i=0;i--) #define sync ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0) #define all(v) v.begin(),v.end() #define S second #define F first #define tci(v,i) for(auto i=v.begin();i!=v.end();i++) #define MOD 1000000007 #define lld long double #define TIMESTAMP cerr<<(((double)clock())/CLOCKS_PER_SEC) #define rep(i,start,lim) for(ll (i)=(start);i<(lim);i++) using namespace std; int32_t main() { sync; ll n,ans=0;cin>>n;ll a[n];rev(i,n)cin>>a[i]; for(ll i=0;i