interface Logger { 
	/**
	* When a process starts, it calls 'start' with processId and startTime.
	*/
	void start(String processId, long startTime);
	
	/**
	* When the same process ends, it calls 'end' with processId and endTime.
	*/
	void end(String processId, long endTime);

	/**
	* Prints the logs of this system sorted by the start time of processes in the below format
	* {processId} started at {startTime} and ended at {endTime}
	*/
	void print();
}

Logger log = new MyLogger();
log.start("1", 100);
log.start("2", 101);  
log.end("2", 102);
log.start("3", 103);
log.end("1", 104);
log.end("3", 105);
log.print();

Output: 
1 started at 100 and ended at 104
2 started at 101 and ended at 102
3 started at 103 and ended at 105