推了一天最后错的？32pts求条

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