#include <iostream>
#include <iomanip>
#include <string>

using namespace std ;

/*****************************************************************************

   print the gcd procedure


           1 |        1 2 0 |          7 8 |  1
             |          7 8 |          4 2 |
             | ------------ | ------------ |
           1 |          4 2 |          3 6 |  6
             |          3 6 |          3 6 |
             | ------------ | ------------ |
             |            6 |            0 | 

  ==> GCD = 6


*****************************************************************************/


// 對調兩整數
void swap( int& a , int& b ) {
    int c = a ;
    a = b ;
    b = c ;
}

// 取出整數 no 的第 n 位數
inline int  nth_digit( int no , int n ) {
    for ( int i = 1 ; i < n ; ++i ) no /= 10 ;
    return ( no % 10 ) ;
}

// 計算整數 no 的位數
inline int  digits_no( int no ) {
    int i ;
    for ( i = 0 ; no != 0 ; ++i ) no /= 10 ;
    return i ;
}

// 整數轉字串, 且在數字之間加上空格
string  convert_string( int number ) {

    if ( number == 0 ) return string(" 0") ;
    
    string space = " " ;
    string no ;
    int na = digits_no(number) ;
    
    for ( int i = na ; i >= 1 ; --i ) {
        no += space + static_cast<char>('0'+nth_digit(number,i)) ;
    }
    
    return no ;
    
}

// 列印計算 gcd 過程
void  print_gcd( int x1 , int x2 ) {
    
    int x3 = x1 ;
    int a1 , a2 , c1 , c2 , e1 , e2 , gcd ;
    
    string  line(12,'-') ;


    if ( x1 < x2 ) swap( x1 , x2 ) ;
    
    cout << endl ;
    
    while ( x1 * x2 != 0  ) {

        a1 = x1/x2 ;
        c1 = a1*x2 ;
        e1 = x1%x2 ;
        
        if ( e1 == 0 ) {
            gcd = x2 ;
        } else {
            
            a2 = x2/e1 ;
            c2 = a2*e1 ;
            e2 = x2%e1 ;
            
            if ( e2 == 0 )  gcd = e1 ;
            
        }

        cout << setw(2*6) << convert_string(a1) << " | " 
             << setw(2*6) << convert_string(x1) << " | " 
             << setw(2*6) << convert_string(x2) << " | " ;

        if ( e1 != 0 ) cout << convert_string(a2) ;

        cout << endl ;
        
        cout << setw(2*6) << " " << " | " 
             << setw(2*6) << convert_string(c1) << " | " ;
        
        if ( e1 != 0 ) 
            cout << setw(2*6) << convert_string(c2) ;
        else
            cout << setw(2*6) << " " ;
        
        cout << " |\n" 
             << setw(2*6) << " " << " | " 
             << setw(2*6) << line << " | " ;

        if ( e1 == 0 ) 
            cout << setw(2*6) << " " << " |\n" ;
        else           
            cout << setw(2*6) << line << " |\n" ;
        
        
        x1 = e1 ;
        x2 = e2 ;
        
        if ( e1 == 0 ) {
            cout << setw(2*6) << " " << " | " << setw(2*6) << 0 
                 << " | " << setw(2*6) << " " << " | " << endl ;
        } else if ( e2 == 0 ) {
            cout << setw(2*6) << " " << " | " 
                 << setw(2*6) << convert_string(x1)  
                 << " | " << setw(2*6) << 0 << " | " << endl ;
        }
        
    }

    cout << "\n==> GCD = " << gcd << "\n\n" ;
    
}


int main() {
    
    int  a , b ;
    
    while (1) {

        cout << "> input two numbers : " ;
        cin >> a >> b ;
        print_gcd(a,b) ;

    }

    return 0 ;
    
}