code

#include <iostream>
using namespace std;

int biggestDigit(int x);
bool isPrime(int x);

int main() {
  int x = 0;
  while (x < 1000) {
    cout << "Please enter an integer greater than 1000: ";
    cin >> x;
  }
  cout << "The largest digit in " << x << " is: " << biggestDigit(x) << endl;
  cout << "List of Prime Numbers from 1 to 100:";
  for (int i = 1; i <= 100; i++) {
    if (isPrime(i))
        cout << " "  << i;
  }
  cout << endl;
  return 0;
}

int biggestDigit(int x) {
  int max = 0;
  int current;
  while (x != 0) {
    current = x % 10;
    if (current > max) {
      max = current;
    }
    x /= 10;
  }
  return max;
}

bool isPrime(int x) {
  if (x < 2) {
      return false;
  }
  for (int i = 2; i < (x / 2 + 1); i++) {
    if (x % i == 0) {
      return false;
     }
  }
  return true;
}