#include <iostream>

using namespace std ;

int main()
{
    int level = 1;
    char suffix = '\0';    //Empty string.

    for (int counter=1;counter<11;counter++) {
        cout << counter << suffix;
        suffix = ' ';
        if ((int)((level*level + level)/2) == counter) {
            cout << endl;
            level++;
        }
    }
    return 0;
}

char suffix = '\0';    //Empty string.

String suffix = "\n"; //go to next line