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#include <iostream>
#include <vector>
#include <iomanip>
#include <string>
#include <cmath>
#include <algorithm>

using namespace std;

void sieve(int x);
void print(vector<string> str);
int user_input();
int main(){
    // call the sieve function and ask for user input
    sieve(user_input());
    return 0;
}

// function that takes user input
int user_input(){
    //variable to put user's input
    int x;
    cout << "Enter a number: ";
    cin >> x; // store user input
    cout << endl;
    return x; // return user inpit
}

void sieve(int x){
    // declare vectors to store respected data
    vector<int> table;
    vector<string> marked_table;

    // store x values inside the vectors
    for(int i = 1; i <= x; i++){
        table.push_back(i);
        marked_table.push_back(to_string(i));
    }

    // marking index(0) since 1 is always composite
    replace(marked_table.begin(), marked_table.end(), marked_table.at(0), "[" + to_string(1) + "]");

    for(int j = 2; j <= sqrt(x); j++){               //loop until j is equals to sqrt(x) times
        if(table.at(j-1)){                               //if reading element
            for(int k = j; (k * j) <= x; k++){              //iterate until k*j < x
                if( (k * j) % (table.at(j-1)) == 0){    //if remainder none
                   for(int l = 2 ; l <= x; l++){        // loop till it reaches x
                       if(table.at(l-1) == k*j){// if table element == k*j
                           // then MARK that table element.
                           replace(marked_table.begin(), marked_table.end(), marked_table.at(l-1), "[" + to_string(k*j) + "]");
                       }
                   }
                }
            }
        }
    }
    // call the print function to print table to terminal
    print(marked_table);
}

void print(vector<string> str){
    int counter = 0;    //declared a counter for table formatting
    for(auto print : str){  // for each loop to print all elements of the vector
        cout << setfill(' ') << setw(10) << print;  // used IOMANIP library functions to format the table uniformly
        counter++; // iterate counter by 1
        if(counter == 10){  // if counter is equal to 10
            // then linebreak
            cout << endl;
            counter = 0;    // reset counter to 0
        }
    }
}