#include<bits/stdc++.h>
using namespace std;
int main(){
	int m,t,s;
	cin>>m>>t>>s;
	double x,y;
	x=s/t;
	if(t==0||x>=m){
		cout<<"0"<<endl;
	}
	else{
		y=m-x;
		y=floor(y);
		cout<<y;
	}
	return 0;
}