de_3.cpp

#include <bits/stdc++.h>
using namespace std;

int main() {
  int n, cnt = 0;
  float a[100], sum = 0, ma = INT_MIN;
  cout << "Nhap n: "; cin >> n;
  for (int i = 0; i < n; i++) {
    cout << "Nhap a[" << i << "]: "; cin >> a[i];
    if (i % 2 == 0) {
      sum += a[i]; cnt++;
    }
    else if (ma < a[i]) ma = a[i];
  }
  cout << "TBC cac so o vi tri chan: " << sum / cnt << endl;
  cout << "So co GTLN o vi tri le: " << ma;
}