#include<bits/stdc++.h> using namespace std; int main(){ long long n,x,y; cin>>n>>x>>y; if(y%x==0){ if(0>n-y/x)cout<<0; else cout<<n-y/x; } else{ if(0>n-y/x)cout<<0; else cout<<n-y/x-1; } return 0; }