C++ :

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

Python :

# coding=utf-8
n=int(input())
x=int(input())
y=int(input())
z=n-y/x
print(int(z))