triangle rectangle de 1 à n puis n-1 à 1 etc

/**
 * Auto-generated code below aims at helping you parse
 * the standard input according to the problem statement.
 **/

const n = parseInt(readline());
k=0
for(i=n; i>= 1; i--)
{
    l = '';
    if(k%2==0)
        for(j = 1; j <= i; j++)
            l += j
    else
        for(j = i; j >= 1; j--)
            l += j
    k++
    print(l)
}