#include <cstdio>
#include <algorithm>

int N, sum;
int A[101];

int main(){
    scanf("%d", &N);

    for(int i=1;i<=N;i++){scanf("%d", A+i); sum += A[i];}

    int M;
    {
        int lb = 0, ub = 101;
        while(ub - lb > 1){
            int mid = (lb+ub) / 2;
            if(mid*mid <= sum){lb = mid;}
            else{ub = mid;}
        }

        M = lb - 1;
    }
    // printf("%d\n", M);
    
    int res = 0;
    for(int i=1;i<=N;i++){
        int expected = i<=M?i:(i<=2*M+1?2*M+2-i:0);
        // printf("%d: %d, %d, %d, %d\n", i, A[i], expected, stock, res);

        if(A[i] >= expected){
            res += std::abs(A[i] - expected);
        }
    }

    printf("%d\n", res);
}