#include <iostream>
using namespace std;
 
int main() {
    int number;
    int sum = 0;
 
    // Ask for input
    cout << "Enter a positive integer: ";
    cin >> number;
 
    // Input validation
    while (number < 0) {
        cout << "Invalid input! Please enter a positive integer: ";
        cin >> number;
    }
 
    // Loop to calculate sum
    for (int i = 1; i <= number; i++) {
        sum += i;
    }
 
    // Display result
    cout << "The sum of numbers from 1 to " << number << " is: " << sum << endl;
 
    return 0;
}
 

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