#include using namespace std; typedef pair P; typedef long long ll; typedef long double ld; const int inf=1e9+7; const ll longinf=1LL<<60; #define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i ) #define rep(i,n) REP(i,0,n) #define F first #define S second constexpr char ln = '\n'; const int mx=200010; const ll mod=1e9+7; int main(){ ll n; cin >> n; vector a(n); rep(i,n){ cin >> a[i]; } ll ans = 0; rep(i,n){ ans += a[i]*(i+1)*(n-i); } cout << ans << ln; return 0; }