#include<iostream>
#include<cstdio>
#include<vector>
#include<algorithm>
#include<cassert>
using namespace std;
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)
const int mod = 1000000007;
const int inf = 1ll << 61;
typedef pair<int, int> P;
typedef pair<int, P>PP;
int v[100006];
signed main() {
	int n; cin >> n;
	rep(i, n)cin >> v[i];
	int sum = -n*(n + 1) / 2;
	rep(i, n)sum += v[i];
	cout << sum << endl;
}

### Prompt

Create a solution in CPP for the following problem:

Gag

Segtree has $ N $ of "gags", each with a value of $ V_i $.

Segtree decided to publish all the gags in any order.

Here, the "joy" you get when you publish the $ i $ th gag to the $ j $ th is expressed as $ V_i --j $.

Find the maximum sum of the "joy" you can get.

input

Input is given from standard input in the following format.


$ N $
$ V_1 $ $ V_2 $ $ \ ldots $ $ V_N $


output

Please output the maximum value of the sum of "joy". However, the value does not always fit in a 32-bit integer.

Insert a line break at the end.

Constraint

* $ 1 \ leq N \ leq 10 ^ 5 $
* $ 1 \ leq V_i \ leq 10 ^ 5 $
* All inputs are integers.



Input example 1


1
59549


Output example 1


59548


Input example 2


Five
2 1 8 5 7


Output example 2


8






Example

Input

1
59549


Output

59548

### Response

```cpp
#include<iostream>
#include<cstdio>
#include<vector>
#include<algorithm>
#include<cassert>
using namespace std;
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)
const int mod = 1000000007;
const int inf = 1ll << 61;
typedef pair<int, int> P;
typedef pair<int, P>PP;
int v[100006];
signed main() {
	int n; cin >> n;
	rep(i, n)cin >> v[i];
	int sum = -n*(n + 1) / 2;
	rep(i, n)sum += v[i];
	cout << sum << endl;
}

```