Помогите пожалуйста написать код на C++

#include <iostream>
#include <ctime>
#include <cstdlib>

using namespace std;

int n,m;

void create(int ** A)
{
srand(time(nullptr));
rand();
for(int x = 0; x < n; x++)
for(int y = 0; y < m; y++)
A[x][y] = rand() % 35 - 17;
}

void print(int ** A)
{
for(int x = 0; x < n; x++)
{
for(int y = 0; y < m; y++)
cout << A[x][y] << '\t';
cout << endl;
}
cout << endl;
}

void sdvig(int ** A)
{
int tmp1,tmp2;
for(int x = 0; x < n; x++)
{
for(int y = 0; y < m; y++)
{
if(x == 0 && y == 0)
{
tmp1 = A[0][0];
A[0][0] = A[n-1][m-1];
}
else if(x == n - 1 && y == m - 1)
{
A[x][y] = tmp1;
}
else
{
tmp2 = A[x][y];
A[x][y] = tmp1;
tmp1 = tmp2;
}
}
}
}

int main()
{
do
{
cout << "n: ";
cin >> n;
}while(n < 1);
do
{
cout << "m: ";
cin >> m;
}while(m < 1);
int ** A;
A = new int*[n];
for(int x = 0; x < n; x++)
A[x] = new int[m];

create(A);
print(A);
sdvig(A);
print(A);

if(A != (int**) nullptr)
{
for(int x = 0; x < n; x++)
{
if(A[x] != (int*) nullptr)
{
delete [] A[x];
A[x] = (int*) nullptr;
}
else exit(1);
}
delete [] A;
A = (int**) nullptr;
}
else exit(1);
return 0;
}