#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0; i<(n); i++)

int main(){
	int a,b; cin>>a>>b;
	
	int ans=50*a;
	double c=(double)0.2*b+0.8;
	c=ans/c;
	ans+=c;
	cout << ans << endl;
}