#include<bits/stdc++.h>
using namespace std;
typedef tuple<long double, long long,long long> tp;
bool cmp(tp T1, tp T2, long long grad, long long constant){
long double m1, c1, m2, c2;
long double temp;
tie(temp,m1,c1) = T1;
tie(temp,m2,c2) = T2;
return (constant - c2)*(m1 - grad) < (constant - c1)*(m2 - grad);
}
long double intersect(tp T1, tp T2){
long double m1, c1, m2, c2;
long double temp;
tie(temp,m1,c1) = T1;
tie(temp,m2,c2) = T2;
return (long double)(c1-c2)/(long double)(m2-m1);
}
inline long long readInt() {
long long x = 0;
char ch = getchar();
while (ch < '0' || ch > '9') ch = getchar();
while (ch >= '0' && ch <= '9'){
x = (x << 3) + (x << 1) + ch - '0';
ch = getchar();
}
return x;
}
long long solve(int n, vector<long long> T){
vector<long long> dp;
deque<tp> convexHull; //intersect, gradient, constant
long long curMax = 0;
dp.push_back(0);
convexHull.push_back(make_tuple(2e9,0ll,0ll));
long long curDpVal;
for(int i = 1; i <= n; i++){
long long curT = T[i];
if(curT >= curMax){
curMax = curT;
while(get<0>(convexHull.front())<(long double)curMax)convexHull.pop_front();
long double temp;
long long grad,constant;
tie(temp, grad, constant) = convexHull.front();
curDpVal = n*curMax + grad * curMax + constant;
}
dp.push_back(curDpVal);
long long grad = -i;
long long constant = dp[i];
while(convexHull.size() >= 2 && cmp(convexHull[convexHull.size()-2],convexHull.back(),grad,constant)){
convexHull.pop_back();
}
tp newLine = make_tuple(2e9,grad,constant);
get<0>(convexHull.back()) = intersect(convexHull.back(),newLine);
convexHull.push_back(newLine);
}
return dp[n];
}
int main(){
int n;
n = readInt();
vector<long long> T(n+1);
for(int i = 1; i <= n; i++) T[i]=readInt();
long long answer = solve(n, T);
cout << answer;
}
