#include <iostream>
using namespace std;
 
void replaceSpace(string& s)
{
	int count = 0;
	for(int i = 0; i<s.length(); i++)
	{
		if(s[i] == ' ')
			count++;
	}
 
	int new_size = s.length() + count * 2;
	s[new_size] = '\0';
 
	for(int i = s.size() - 1; i >= 0; i--)
	{
		if(s[i] == ' '){
			s[--new_size] = '0'; 	
			s[--new_size] = '2';
			s[--new_size] = '%';
		}else {
			s[new_size] = s[i];	
			new_size--;
		}
	}
}
 
int main() {
	// your code goes here
	string s = "how are you doing?";
	cout << s << endl;
	replaceSpace(s);
	cout << s << endl;
	return 0;
}