#include "bits/stdc++.h"
using namespace std;

int main() {
    int n, sum=0;
    vector<int> a;
    cin >> n;
    for(int i=0; i<n; i++) {
        int t;
        cin>>t;
        sum += t;
        a.push_back(t);
    }
    int x = (int)sqrt(sum+0.1);
    int ans = 0;
    for (int i=0; i<n; i++) {
        ans += max(0, a[i] - max(0, x - abs((x - 1) - i)));
    }
    cout<<ans<<endl;
    return 0;
}