Check when is the first time an element appears in an array

#include <iostream>
using namespace std;
int main()
{
    int b, n, index=0;
    cout << "How many numbers will you check: "<<endl;
    cin >> n;
    int* a;
    a = new int[n];
    cout << "What is the element you want to check: "<<endl;
    cin >> b;
    for (int i = 0; i < n; i++) { //loop for element input
        cout << "Enter an element: " << endl;
        cin >> a[i];
    }
    for (int i = 0; i < n; i++) {//loop for checking the key element
        if (a[i] == b) {
            index = i;
            break;
        }
    }
    cout << "The element appears for the first time at number: " << index + 1;
}