#include <stdio.h>
#include <assert.h>
#include <math.h>

long double round_f(long double number, int decimal_places)
{
	assert(decimal_places > 0);
	
	double power = pow(10, decimal_places-1);
	number *= power;
	
	return (number >= 0) ? ((long long)(number + 0.5))/power : ((long long)(number - 0.5))/power;
}

int main(void)
{
	printf("%Lf\n", round_f(1.24, 2));
	printf("%Lf\n", round_f(1.25, 2));
	printf("%Lf\n", round_f(1.25, 1));
	printf("%Lf\n", round_f(1.55, 1));

	return 0;
}