LCM-GCD

#include <iostream>
using namespace std;

int main() {
    int arr[10] = {0}, n, LG, LCM, GCD, i, j;

    while(true) {
        cout << "OPERATIONS" << endl;
        cout << "1. LCM (Lowest Common Multiple)" << endl;
        cout << "2. GCD (Greatest Common Divisor)" << endl;
        cout << "0. Exit." << endl;
        cout << "Enter Choice: ";
        cin >> LG;

        if(LG == 1 || LG == 2) {
            while(true) {
                cout << "How Many Elements? (Maximum 10) : ";
                cin >> n;
                if(n > 10 || n < 1)
                    cout << "Invalid Input. Try Again." << endl;
                else
                    break;
            }
            cout << "Enter the Elements (Only Non-Zero Positive Integers): ";

            for(i = 0; i < n; i++)
                cin >> arr[i];
            LCM = 9999, GCD = -1;
            for(i = 0; i < n; i++) {
                while(true) {
                    if(arr[i] < 1) {
                        cout << "Element no. " << i + 1 << " is invalid. Renter The Element: ";
                        cin >> arr[i];
                    }
                    else {
                        if(arr[i] < LCM) LCM = arr[i];
                        if(arr[i] > GCD) GCD = arr[i];
                        break;
                    }
                }
            }

            if(LG == 1) {
                for(i = LCM; ; i++) {
                    for(j = 0; j < n; j++)
                        if(i % arr[j] != 0) break;
                    if(j == n) {
                        LCM = i;
                        break;
                    }
                }
                cout << "LCM = " << LCM << endl << endl << endl;
            }

            else {
                for(i = GCD; i > 0; i--) {
                    for(j = 0; j < n; j++)
                        if(arr[j] % i != 0) break;
                    if(j == n) {
                        GCD = i;
                        break;
                    }
                }
                cout << "GCD = " << GCD << endl << endl << endl;
            }
        }
        else if(LG == 0) break;

        else cout << "Invalid Choice. Try Again." << endl << endl;

    }
    return 0;
}