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

int main()
{
    int N;
    cin >> N;
    vector<int> A(N);
    for (int i = 0; i < N; i++)
    {
        cin >> A[i];
    }
    long long ans = 0;
    int maru = 0;

    for (int i = 0; i < N; i++)
    {
        if (A[i] > N)
        {
            ans += A[i] - (N + 1) - maru + 1;
            maru++;
        }
    }
    cout << ans;
}