can you help me please? Why doesn't this code work?

Question

#include <iostream>
using namespace std;

int** constructor(int n,int m){
int*z=new int *[m];
for (int i=0;i<m;i++)
z[i]=new int[n];
for (int i=0;i<m;i++)
{
for(int j=0;j<n;j++)
z[i][j]=i+3*j;
}
return z;
}
int calculator(int**key,int m,int n){
int count=1;
for (int i=0;i<m;i++){
for(int j=0;j<n;j++){
if(key[i][j]!=0)
{count=count*key[i][j];
}
}
}
return count;
}
void show(int** key,int m,int n){
for(int i=0;i<m;i++){
cout<<endl;
for(int j=0;j<n;j++)
cout<<"\t"<<key[i][j];

}
}
void calcshow(int m){
cout<<endl<<"\n"<<"\t"<<m<<"\n"<<"\n";
}
int main() {
int m=5;
int n=6;
int** z=constructor(m,n);
int b=calculator(z,m,n);
show(z,m,n);
calcshow(b);
return 0;
}

Answer 1

change line 5 to: int**z=new int *[m];

Answer 2

What is the expected action?