C++ :

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

Python :

# coding=utf-8
n,x,y = input().split ()
n = int (n)
x = int (x)
y = int (y)
a = int (y / x)
print (y - a)