#include <iostream>
#include <ctime>
#include <cstdlib>
#include <iomanip>
#include <cmath>
 
bool is_prime(int value)
{
    if(value <= 1)
    {
        return 0;
    }
    
    for(int i = 2; i <= sqrt(value); ++i)
    {
        if (value % i==0)
        {
            return 0;
        }
    }
    
    return 1;
}
 
int sum_before(int * arr, int index)
{
    int sum = 0;
    
    for(int i = 0; i < index; ++i)
    {
        sum += arr[i];
    }
    
    return sum;
}
 
void change_elems(int ** matrix, int rows, int cols)
{
    int * diag = new int[rows];
    
    for(int i = 0; i < rows; ++i)
    {
        diag[i] = matrix[i][i];
    }
    
    for(int i = 0; i < rows; ++i)
    {
        if(is_prime(matrix[i][i]))
        {
            matrix[i][i] = sum_before(diag, i);
        }
    }
    
    delete [] diag;
        
}
 
void fill_matrix(int ** matrix, int rows, int cols)
{
    for(int i = 0; i < rows; ++i)
    {
        for(int j = 0; j < cols; ++j)
        {
            matrix[i][j] = rand() % 100;
        }
    }
}
 
void output_matrix(int ** matrix, int rows, int cols)
{
    for(int i = 0; i < rows; ++i)
    {
        for(int j = 0; j < cols; ++j)
        {
            std::cout << std::setw(4) << matrix[i][j] << " ";
        }
        std::cout << "\n";
    }
}
        
 
int main()
{
    srand(static_cast<unsigned int>(time(0))); 
    
    int rows, cols;
 
    std::cout << "Enter rows: ";
    std::cin >> rows;
    std::cout << "Enter cols: ";
    std::cin >> cols;
 
    int ** matrix = new int * [rows];
 
    for(int i = 0; i < rows; ++i)
        matrix[i] = new int[cols];
        
    
    fill_matrix(matrix, rows, cols);
    std::cout << "Source:\n";
    output_matrix(matrix, rows, cols);
    
    change_elems(matrix, rows, cols);
    std::cout << "\nResult:\n";
    output_matrix(matrix, rows, cols);
    
   
    for(int i = 0; i < rows; ++i)
        delete [] matrix[i];
        
    delete [] matrix;
   
    return 0;
}