exercise

#include<iostream>
using namespace std;
//i must use 5 loops for this exercise! Thank you all!

int main() {
int a; cout << "size array:" << endl; cin >> a;
int b [a], c[a] , *d = new int[2*a]; //pointer is twice the size of arrays
int f = -1;
int k = 0;

cout << endl;

//I must initialized two array, the second with the opposite value of the first.

    for(int e=0; e < a ; e++){int i; cout << "init. first array:" << endl; cin >> i; b[e] = i;}
    for(int e : b) { f++; c[f] = -e;} //cout << c[f] << endl

//now i must initialized the pointer's first half value with the sum of the respective value for each position in arrays

    do
         d[k] = b[k] + c[k];
    while( ++ k < a);

//now the second half but with difference


        while(k++ < 2*a)  d[k] = b[k] - c[k];

//result it has to be 4 numbers: a -a 0 2a
for(int e=0,m=a; e < a; e++, m++) { cout << b[e] << " "<< c[e] <<" "<< d[e] <<" "<< d[m] << endl;}





}