#include <stdio.h>
#include <string.h>
void func(char *s)
{
    int n = strlen(s);
    printf("input  = %s\n", s);
    for (int i = 1; i <= n / 2; ++i)
    {
        if (n % i == 0)
        {
            if (strncmp(s, s + i, strlen(s + i)) == 0)
            {
                printf("repeat = %.*s\n\n", i, s);
                return;
            }
        }
    }
    printf("repeat unit not found!\n\n");
    return;
}
int main()
{
    func("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
    func("123412312341231234123123412312341231234123");
    func("oxoxoxoxoxoxoxoxxoxoxoxoxoxoxoxoxx");
    func("axaxa"); // repeat = ax
    return 0;
}