pb1 10/8/2019

#include <iostream>
#include <cstring>
#include <stdio.h>
using namespace std;

int main()
{
    int n;
    char s[256];
    cin >> n;
    getchar();
    gets(s);
    char sep[] = " .,", *p;
    p = strtok(s, sep);

    while (p)
    {
        if (strlen(p) == n)
            cout << p << endl;
        p = strtok(NULL, sep);
    }
    return 0;
}