Need an input validation loop for intro to c++

/Program to write sum of first N natural numbers using C++.

#include using namespace std; int main() { int num, sum=0; cout>num; //checking if the user input is negative or positive number if(num

1. Sum of Numbers Write a program that asks the user for a positive integer value. The program should use a loop to get the sum of all the integers from 1 up to the number entered. For example, if the user enters 50, the loop will find the sum of 1, 2, 3, 4, ... 50. Input Validation: Do not accept a negative starting number