#include <bits/stdc++.h>

using namespace std;
 
using ll = long long;
using ull = unsigned long long;
using ldouble = long double;
 
const ll inf = 1ll << 60;
const ll mod = (ll)1e9 + 7;

#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define print(s) cout << s;
#define println(s) cout << s << endl;
#define printd(s) cout << fixed << setprecision(10) << s << endl;

string res;

int main()
{
    ll a, b;
    cin >> a >> b;

    println(2*b - a);
}

#include<stdio.h>

int main(){

	char word1[105];
	char word2[105];
	
	scanf ("%s %s", &word1, &word2);
	printf("%s%s\n",word2,word1);
	
	return 0;
}