interface AdvancedArithmetic{
    divisorSum(n: number): number;
}

class Calculator implements AdvancedArithmetic
{
    divisorSum(n: number): number {
        let sum = 0
        
        for (let i = 1; i < (n + 1) / 2; i++) {
            if (n % i === 0) {
                sum += i
            }
        }
        
        return sum + n
    }
}