#include <stdio.h>

int main(void) {
	int start_index = 1;
	int length = 6;
	char inputline[] = "This is my day in 2020 1230023";
	
    
    printf("%.*s\n", length, inputline + start_index); //  you can use fprintf(outfile, "%s", substr); here
	return 0;
}