#include <iostream>
#include <algorithm>
#include <string>
 
int main() {
	std::string str = "                                                         ";
	std::cout<<str<<"<-"<<std::endl;
	size_t endpos = str.find_last_not_of(" \t");
	size_t startpos = str.find_first_not_of(" \t");
   	if( std::string::npos != endpos )
	{
    	str = str.substr( 0, endpos+1 );
    	str = str.substr( startpos );
	}
	else{
		str.erase(std::remove(std::begin(str), std::end(str), ' '), std::end(str));
	}
	std::cout<<str<<"<-";
	return 0;
}

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