#include <iostream>
#include <vector>
using namespace std;
 
int minCost(vector<int>& cost, int n) { 
    vector<int> dp(n+1,0); 
    for(int i=2;i<=n;++i){ 
        dp[i] = min(dp[i-1]+cost[i],dp[i-2]+cost[i-1]*cost[i]); 
    } 
    return dp[n]; 
}
 
int main() {
    int n;
    cin >> n;
    vector<int> cost(n+1);
    for(int i=1;i<=n;i++)
        cin >> cost[i];
    cout << minCost(cost,n) << endl;
    return 0;
}