#include <iostream>
using namespace std;

int main()
{  double initial_balance = 10000;
   double balance = initial_balance;
   int year = 0;

   while (balance < 2 * initial_balance)
   {  balance = balance * (1 + rate / 100);      
      year++;
   } 
   cout << "The investment doubled after " 
        << years << " years.\n";
   return 0;
}