06. Sum Prime Non Prime

#include <iostream>
#include <string>
#include <cmath>

using namespace std;

int main () {

    string input;
    cin >> input;

    int prime = 0;
    int nonPrime = 0;

    while(input != "stop") {
        int number = stoi(input);

        if(number >= 0) {
            bool isPrime = true;
            for(int i = 2; i <= number / 2; ++i) {
                if(number % i == 0) {
                    isPrime = false;
                    break;
                }
            }
            if(isPrime) {
                prime += number;
            } else {
                nonPrime += number;
            }
        } else {
            cout << "Number is negative." << endl;
        }
        cin >> input;
    }

    cout << "Sum of all prime numbers is: " << prime << endl;
    cout << "Sum of all non prime numbers is: " << nonPrime << endl;

    return 0;
}