#include<stdio.h>
int main(void){
int A, B;
scanf ("%d%d", &A, &B);
if ( A < B && A + 1 != B){
	printf ( "%d\n", B - 2);
}else if ( B < A && A != B + 1){
	printf ( "%d\n", 1999999999 - B);
}
	return 0;
}