import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StreamTokenizer;
import java.util.ArrayList;
import java.util.Scanner;

/**
 * @author iceewei
 * @Description: 大整数算法 acwing-ycx
 * @date 2025/1/17
 */
public class Main {

    public static void main(String[] args) throws IOException {
        String[] s = doInput();
        ArrayList<Integer> A = new ArrayList<>();
        ArrayList<Integer> B = new ArrayList<>();
        for (int i = s[0].length() - 1; i >= 0 ; i--) A.add(s[0].charAt(i) - '0');
        for (int i = s[1].length() - 1; i >= 0 ; i--) B.add(s[1].charAt(i) - '0');
        ArrayList<Integer> C = minus(A, B);
        for (int i = C.size() - 1; i >= 0; i--) {
            if (i == C.size() - 1 && C.get(i) == -1) System.out.print("-");
            else System.out.print(C.get(i));
        }
    }

    // 关键是将问题转化为三个数相加，Ai+Bi+t
    private static ArrayList<Integer> minus(ArrayList<Integer> A, ArrayList<Integer> B) {
        if (!more(A, B)) {
            ArrayList<Integer> minus = minus(B, A);
            minus.add(-1);
            return minus;
        }
        ArrayList<Integer> C = new ArrayList<>();
        int t = 0;
        for (int i = 0, j = 0; i < A.size() || j < B.size(); i++, j++) {
            int remain = A.get(i) - (j < B.size()?B.get(j):0) - t;
            if (remain >= 0) {
                C.add(remain);
                t = 0;
            } else {
                C.add((remain + 10) % 10);
                t = 1;
            }
        }
        while (C.size() > 1 && C.get(C.size() - 1) == 0) C.remove(C.size() - 1);
        return C;
    }

    private static boolean more(ArrayList<Integer> A, ArrayList<Integer> B) {
        if (A.size() != B.size()) return A.size() > B.size();
        for (int i = A.size() - 1, j = B.size() - 1; i >= 0 && j >= 0; i--, j--) {
            if (A.get(i) != B.get(i))
                return A.get(i) > B.get(i);
        }
        return true;
    }

    private static String[] doInput() throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] s = new String[2];
        int counter = 0;
        String ss;
        while ((ss = br.readLine()) != null) {
            s[counter++] = ss;
        }
        return s;
    }
}