A3

#include <stdio.h>

change(char *be, char *ki, int n)
{
    int sz = 0;
    int k = 0;

    for (int i = 0; be[i] != '\n'; i++)
    {
        if (sz % n == 0)
        {
            ki[k] = be[i];
            k++;
        }
        if (be[i] == ' ')
        {
            sz++;
        }
    }
    ki[k-1] = '\0';

}

int main()
{
    char ch[50];
    char chki[50];

    fgets(ch, 50, stdin);

    change(ch, chki, 3);

    printf("%s", chki);

    return 0;
}