int main(){ 

   int a[100]; 

   int n;  

  printf("Nhap so luong phan tu n = "); 

   do{        scanf("%d", &n);   

     if(n <= 0){            printf("Nhap lai n = ");    

    while(n <= 0);  

      for(int i = 0; i < n; i++){     printf("Nhap a[%d] = ",i); 

       scanf("%d", &a[i]);  

  Sap xep dung thuat toan sap xep chon    int tg; 

   for(int i = 0; i < n - 1; i++)

    for(int j = i + 1; j < n; j++)

        if(a[i] > a[j]){        

     Hoan vi 2 so a[i] va a[j]  

              tg = a[i];            

    a[i] = a[j];            

    a[j] = tg;                  

     printf("Mang da sap xep la: ");   

 for(int i = 0; i < n; i++)

   printf("%5d", a[i]);