#include<bits/stdc++.h>
using namespace std;
int main(){
    int a,b,x,mx=0;
	cin>>a>>b>>x;
	for(int i=b;i<=x;i++) if(i%a>mx) mx=i%a;
	cout<<mx;
}
   
/**************************************************************
	Problem: 2401
	User: panyuchen
	Language: C++
	Result: Time Limit Exceed
****************************************************************/