c++ novice scanf_s C6066, C6273, C6328 error question

#include <iostream>
using namespace std;
int main() {
    cout <<" Copy the word 'two' as it is entered. Just use two words. \n"<< endl;
    char a1[1000] = { 0 };
    char a2[1000] = { 0 };
    cin >> a1 >> a2;
    cout << a1 << " " << a2 << endl;
}

#include <stdio.h>

int main() {

    printf (copy the 'two' words exactly as you entered them. Just use two words.\n");
    char a1[1000] = { 0 };
    char a2[1000] = { 0 };
    scanf_s("%s %s",a1,a2,sizeof(a1),sizeof(a2));
    printf("\n%s %s", a1, a2);

}

C6066 : An item other than a pointer has been passed to _Param_(4).
C6273: Non-integer item passed to _Param_(3).

C6328: Size mismatch: 'unsigned__int64' passed to _Param_(5).