/******************************************************************************

Welcome to GDB Online.
GDB online is an online compiler and debugger tool for C, C++, Python, PHP, Ruby,
C#, VB, Perl, Swift, Prolog, Javascript, Pascal, HTML, CSS, JS
Code, Compile, Run and Debug online from anywhere in world.

*******************************************************************************/
#include <stdio.h>

int main()
{
    int leng = 20;

    int count = 0;
    int idx[leng];

    // say you meet the dna substring 3 times
    for(int i=0; i<3; i++){
        // you put the index that you found the substring here
        idx[count] = i;
        count++;
    }

    // printing count
    for(int i=0; i<count; i++){
        printf("%d ", idx[i]);
    }

    return 0;
}