#include<iostream>
#include<string>

int main(int argc, char *argv[])
{
    std::string str;
    str = "hello World";
    str += " and hello again";
    std::cout<<str<<"\n";
    str.replace(str.begin(),str.end(),"hello","HELLO");
    std::cout<<str<<"\n";
    return 0;
}