#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i = (a); i < (b); ++i)
#define REP(i,n) FOR(i,0,n)
#define SZ(n) (int)(n).size()
#define ALL(n) (n).begin(), (n).end()
#define MOD 1000000007
using namespace std;
typedef long long LL;
typedef vector<int> VI;

int main() {
	LL a, b;
	cin >> a >> b;
	if (a < b) cout << b - 1 - 1 << endl;
	else cout << 2000000000 - b - 1 << endl;
	return 0;
}