> #include <stdio.h>
> int main ()
> {
> 	int i , s , sum ;
> 	scanf ( "%d" , &s ) ;
> 	for ( sum = 1 , i = 1 ; sum < s || sum > s && ( sum - s ) % 2 ; i ++ , sum += i ) ;
> 	printf ( "%d\n" , i ) ;
> 	return 0 ;
> }