#include <iostream>
#include <cmath>
#include <vector>

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);
    
    int n;
    std::cin >> n;
    std::vector<int> a(200, 0);
    int sum = 0, ans = 0;
    for(int i=0; i<n; ++i){
        std::cin >> a[i];
        sum += a[i];
    }
    int step = std::floor(std::sqrt(sum));
    ans += (sum - step*step);
    for(int i=0; i<std::max(n, 2*step+1); ++i){
        if(i<step){
            ans += std::fabs(a[i]-(i+1));
        }else if(i<2*step-1){
            ans += std::fabs(a[i]-(i+1-(i-step+1)*2));
        }else{
            ans += a[i];
        }
    }
    ans /= 2;
    std::cout << ans << "\n";

    return 0;
}