#include <bits/stdc++.h>
using namespace std;
int main(){
    int N;
    cin >> N;
    int k = 0;
    vector<int> B(101,0);
    int blocksum = 0;
    for(int i=1;i<=N;i++){
        cin >> B[i];
        blocksum += B[i];
    }
    while((k+1)*(k+1)<=blocksum) k++;
    int ans=0;
    vector<int> P(101,0);
    for(int i=1;i<=k;i++){
        P[i] = i;
        P[2*k-i] = i;
    }
    for(int i=1;i<=N;i++){
        if(B[i]>P[i]) ans += B[i] - P[i];
    }
    cout << ans << endl;
    return 0;
}