Difference of Squares

Using the integers from 1 through n, calculate two quantities: first add the integers and square the result; separately square each integer and add those squares. Return the first quantity minus the second.

Implement difference_of_squares(n).

Input

n: The last integer to include.

Output

Return square-of-sum minus sum-of-squares.

Vincoli

0 ≤ n ≤ 50,000. For n = 0, both sums are 0. All required values fit signed 64-bit integers.

Esempi

Input:
n = 4

Output atteso:
expected = 70

Input:
long long n = 4;

Output atteso:
long long expected = 70;

Input:
long n = 4;

Output atteso:
long expected = 70;

Input:
n = 1

Output atteso:
expected = 0

Input:
long long n = 1;

Output atteso:
long long expected = 0;

Input:
long n = 1;

Output atteso:
long expected = 0;

Riferimenti

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• #6 Sum Square Difference
• Difference of Squares