#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <math.h>
#include <stdlib.h>

int main()
{
	unsigned int m, t, s;
	scanf("%d %d %d", &m, &t, &s);
	int c = ceil((double)(s) / t);
	if (t = 0)  //特判
    {
    	printf("0");
    }
	if (m - c > 0)  //吃不完
	{
		printf("%d", m - c);
	}
	else  //吃完
	{
		printf("0");
	}

	return 0;