#include <iostream>
#include <string>

using namespace std;

int main() {
    string name;
    string last_name;
    string first_name;

    int comma;
    int last_start;
    int first_start;

    int last_size;
    int first_size;

    cout << "Enter in a name (last,first): ";
    getline(cin,name);

    // Locate the ,
    comma=name.find(",");
    if(comma==-1) {
        cout << "String error!\nMissing ," << endl;
        exit(-1);
    }
    // Range for the last name.
    last_start=0;
    last_size=comma;

    // Range for the first name.
    first_start=comma+1;
    first_size=name.length()-1-comma;

    last_name=name.substr(last_start,last_size);
    first_name=name.substr(first_start,first_size);

    cout << "Hello " << first_name << " " << last_name << endl;

    return 0;
}