#include<bits/stdc++.h>
using namespace std;
int main(){
	int a=0,b,c;
	cin>>c>>b;
	for(;c<b;c++){
		a=a+30;
	}
	cout<<a;
}
/**************************************************************
	Problem: 1320
	User: zengyixuan
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/