#include <bits/stdc++.h>

using namespace std;

int main()
{
    char *p,s[256],cuv[55][20],aux[256];
    cin.get(s,256);
    int nr=0,i,j;
    for(i=0;s[i];++i)
        if((s[i]==' '&&s[i-1]!=' ')||(s[i]>='a'&&s[i]<='z')||(s[i]>='A'&&s[i]<='Z'))
            aux[nr++]=s[i];
    aux[nr]=NULL;
    strcpy(s,aux);
    p=strtok(s," ");
    nr=0;
    while(p)
    {
        strcpy(cuv[++nr],p);
        p=strtok(NULL," ");
    }
    for(i=1;i<=nr/2;++i)
        cout<<cuv[i]<<'\n'<<cuv[nr-i+1]<<'\n';
    if(nr%2)cout<<cuv[nr/2+1];
    return 0;
}