#include<iostream>
using namespace std;
int ar[20];
int main()
{
    cout << "Please input 20 number to ar.";
    for (int i = 0; i < 20; ++i)
    {
        cin >> ar[i];
    }
    cout << "The maximum number is:" << Max(ar[20]);

    return 0;
}
//Function for Maximum.
int Max(int arr[20])
{
    int max = arr[0];
    for (int j = 1; j < 20; ++j)
    {
        if (arr[j] > max)
            max = arr[j];
    }
    return max;
}