Write a program to display the following pyramid structure using while loop. 1 12 123 1234 12345

Write a program to display the following pyramid structure using while loop. 

1 

12 

123 

1234 

12345
 #include <iostream>

using namespace std;

int main(){

       int a = 1;

       while (a <= 5){

             

              int b = 1;

              while (b <= a){

                     cout << b;

                     b++;

              }

              cout <<endl;

              a++;

       }

       system("pause");

       return 0;

}