#include <bits/stdc++.h>
using namespace std;

int main() {
  int n, k;
  cin >> n >> k;

  cout << 100*n*(n+1)*k/2+n*k*(k+1)/2 << endl;
}
#include<cstdio>
#include<cmath>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<vector>
#include<set>
using namespace std;
#define MAXN 100005
#define lowbit(x) (x&-x)
#define reg register
typedef long long LL;
typedef unsigned long long uLL;
typedef unsigned int uint;
typedef pair<int,int> pii;
const LL INF=0x7f7f7f7f7f7f;
const int mo=998244353;
const double PI=acos(-1.0);
template<typename _T>
_T Fabs(_T x){return x<0?-x:x;}
template<typename _T>
void read(_T &x){
	_T f=1;x=0;char s=getchar();
	while(s>'9'||s<'0'){if(s=='-')f=-1;s=getchar();}
	while('0'<=s&&s<='9'){x=(x<<3)+(x<<1)+(s^48);s=getchar();}
	x*=f;
}
int n,d,h;double maxx;
signed main(){
	read(n);read(d);read(h);
	for(int i=1;i<=n;i++){
		int x,y;read(x);read(y);
		double tmp=1.0*y-1.0*(x)/(d-x)*(h-y);
		maxx=max(maxx,tmp);
	}
	printf("%.3f\n",maxx);
	return 0;
}
