I’m trying to solve a problem on Geeksforgeeks that requires me to make a C++ program that returns the sum of the first ‘n’ integers, my initial approach was to use the Sum of the first n integers = (n*n+1)/2 identity so I wrote the following code:

class Solution {
  public:
    long long seriesSum(int n) {
        
        return ((n)*(n+1)/2);
    }
};

It successfully passes about 15 test cases by then it’s showing an unexpected output when 4407895 is passed as input

For Input: 4407895
Your Output: -444654092
Expected Output: 9714771369460

Why does it return a negative value when two positive values are multiplied?