Найти число отрицательных элементов матрицы [MxN], расположенных в столбцах с номером, кратным A. (3х4) C++

#include <iostream>
using namespace std;

int main() {
    bool checkA = false;
    bool checkB = false;
    int a;
    int b;
    cin >> a >> b;
    cout << "Entered nums: \n";
cout << a << "\n";
cout << b << "\n";
if(a >= 0) {
    checkA = true;
    cout << a << " is >= 0 \n";
}
else {
    checkA = false;
    cout << a << " isn't >= 0 \n -Failed \n";
}
if(b <= 9) {
    checkB = true;
    cout << b << " is <= 9 \n";
}
else {
    checkB = false;
    cout << b << " isn't <= 9 \n -Failed \n";
}
if(checkA&&checkB == true) {
    int sum = a+b;
    cout << "Sum is " << sum;
}
else {
    cout << "\n Wrong nums";
}
}

#include <iostream>
using namespace std;

int main() {
    bool checkA = false;
    bool checkB = false;
    int a;
    int b;
    cin >> a >> b;
    cout << "Entered nums: \n";
cout << a << "\n";
cout << b << "\n";
if(a >= 0) {
    checkA = true;
    cout << a << " is >= 0 \n";
}
else {
    checkA = false;
    cout << a << " isn't >= 0 \n -Failed \n";
}
if(b <= 9) {
    checkB = true;
    cout << b << " is <= 9 \n";
}
else {
    checkB = false;
    cout << b << " isn't <= 9 \n -Failed \n";
}
if(checkA&&checkB == true) {
    int sum = a+b;
    cout << "Sum is " << sum;
}
else {
    cout << "\n Wrong nums";
}
}