#include<bits/stdc++.h> 
using namespace std;
	int main(){
	float n,m,x;
	cin>>n>>m;
	
	x=30*(n-m);
	cout<<x;
	return 0;
  }
    






	

/**************************************************************
	Problem: 1320
	User: zhangchenhao
	Language: C++
	Result: Wrong Answer
****************************************************************/