#include <iostream>
#include <sstream>
#include <math.h>
#include <stack>
#include <set>
#include <algorithm>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <cstdio>
#include <vector>
using namespace std;

#define INF (1 << 30)
#define INFLL (1LL << 60)

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