#include<iostream>
#include<cmath>
using namespace std;
int main(){
	int m,t,s,a,b;
	cin>>m>>t>>s;
	if(t==0){
		cout<<0;
		return 0;
	}
	a=s/t;
	if(s%t!=0)ceil(a);
	b=m-a;
	if(b<0)cout<<0;
	else cout<<b;
	return 0;
}

求调