#include <iostream>
#include <vector>
using namespace std;

int solve(vector<int> A){
    int sum = 0;
    for(int i=0;i<A.size();i++)sum += A[i];
    
    int k = 0;
    while((k + 1) * (k + 1) <= sum)++k;
    
    --k;
    
    vector<int> B(2 * k + 1);
    for(int i=0;i<k;i++)B[i] = B[B.size() - i - 1] = i + 1;
    B[k] = k + 1;
    
    int size = max((int)A.size(), (int)B.size());
    while(A.size() < size)A.push_back(0);
    while(B.size() < size)B.push_back(0);
    
    int res = 0;
    for(int i=0;i<size;i++)if(B[i] < A[i])res += A[i] - B[i];
    
    return res;
}

int main(){
    int N;
    cin >> N;
    
    vector<int> A(N);
    for(int i=0;i<N;i++)cin >> A[i];
    
    cout << solve(A) << endl;
    return 0;
}