#include<stdio.h>
#include<string.h>

bool isInMultiple(char *word1, char *word2){
    int count =0;
    char *temp = word1;
    for (int i=0;i<strlen(word1);i++){
            if (strncmp(&temp[i], word2, 3) == 0)
                count++;
            if (count >=2)
                return true;
    }
    return false;
}

int main (){
    char *word1 = "rskrskrsk";
    char word2 [4] = {0};

    char* checkedStrings = {0};

    char *temp = word1;
    char char1, char2, char3;

    int count =0;
    for (int i = 0; i < (strlen(word1)-3); ++i){
        count = 0;
        strncpy(word2, &temp[i], 3);
        word2[3] = '\0';

        temp = word1;

        if (!strncmp(checkedStrings, word2, 3) && isInMultiple(word1, word2)){
            printf("%s\n", word2);
            strcat(checkedStrings, word2);
        }

    }

    return 0;
}