编写程序输入一个n*n的矩阵，求出两条对角线元素值之和

//编写一个程序输入一个n*n的矩阵，求出两条对角线元素值之和
#include <iostream>
using namespace std;
int main() {
int num;
cout << "请输入对角矩阵的大小" << endl;
cin >> num;
int **p = new int*[num];//数组大小动态，二维
for (int i = 0; i <num; i++)
p[i] = new int[num];
int sum = 0;
int number;
for (int i = 0; i < num; i++) {
cout << "请输入矩阵元素";
cout << "第" << (i + 1) << "行" << endl;
for (int j = 0; j < num; j++){
cout << "第" << (j + 1) << "列" << endl;
cin >> number;
p[i][j] = number;
}
}
for (int i = 0; i < num; i++) {
sum += p[i][i] + p[i][num-i-1];//两个对角线元素相加
}
cout << "sum=" << sum << endl;
return 0;
}