I got a negative number while trying to return a long long value

I created a function seriesSum to return a sum of the series of a number, and I used long long return data type but it returns a negative number if I insert for example 46341 output will be -1073716337 and what I am expected is 1073767311 here is my code:

#include <iostream>
using namespace std;

long long seriesSum(int n)
{return n*(n+1)/2;}

int main()
{
    cout<<seriesSum(46341); // expected 1073767311 but output is -1073716337

    return 0;
}

>Solution :

The argument variable n is an int.

All operations you perform in the function are done using int values. Which you will overflow, leading to undefined behavior.

Change the argument type to unsigned long long.

I also recommend you change the return type to be unsigned as well, if you’re not going to get negative results.