#include<bits/stdc++.h>
#define int long long
#define maxn 1000005
#define endl '\n'
using namespace std;
int a[maxn];
int f[maxn];
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    if(fopen(".inp","r")){
	   freopen(".inp","r",stdin);
	   freopen(".out","w",stdout);
    }
    int n;
    cin>>n;
    int tong=0;
    for (int i=1;i<=n;i++){
    	int x;
    	cin>>x;
    	tong+=(x*(n-i+1) *i);
    }
    cout<<tong<<endl;

	
	

    return 0;
}