// #1

#include
using namespace std;

int main() {
unsigned int n;
cout << "N = ";
cin >> n;
float a[n][n],
sum = 0;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
cout << "a[" << i
<< "][" << j
<< "] = ";
cin >> a[i][j];
sum += a[i][j];
}
}
float avg = sum / (n * n);
cout << "Среднее арифметическое - "
<< avg << ", начинаю замену...\n";
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
if (a[i][j] < 0) {
cout << "a[" << i
<< "][" << j
<< "] = " << a[i][j]
<< " < 0, заменяю на "
<< avg << "...\n";
a[i][j] = avg;
}
}
}
cout << "\nИзменённый массив:\n";
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
cout << a[i][j];
if ( !(j == n - 1) ) cout << ' ';
}
if ( !(i == n - 1) ) cout << '\n';
}
return 0;
}


// #2

#include
using namespace std;
const unsigned short int n = 7;

int main() {
int a[n][n],
max;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
cout << "a[" << i
<< "][" << j
<< "] = ";
cin >> a[i][j];
}
}
max = a[0][0];
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
if ( (a[i][j] > max) && (i + j > n + 1) )
max = a[i][j];
}
}
cout << "Максимум ниже побочной диагонали: "
<< max;
return 0;
}