import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String a = sc.next();
        String b = sc.next();
        List<Integer> A = new ArrayList<>(a.length());
        List<Integer> B = new ArrayList<>(b.length());
        for (int i = a.length() - 1;i>=0;i--) {
            A.add(a.charAt(i) - '0');
        }
        for (int i = b.length() - 1;i>=0;i--) {
            B.add(b.charAt(i) - '0');
        }
        //由于要输出一个数，所以根据结果判断要不要输出负号
        if (!cmp(A,B)) System.out.print("-");
        List<Integer> C = sub(A,B);
        for (int i = C.size() - 1; i >= 0 ; i--) {
            System.out.print(C.get(i));
        }
    }

    public static List<Integer> sub(List<Integer> A,List<Integer> B){
        List<Integer> C = new ArrayList<>();
        if (!cmp(A,B)) return sub(B,A);
        //表示借位的标志位
        int t = 0;
        for (int i = 0; i < A.size(); i++) {
             t = A.get(i) - t;
             if (i < B.size()) t-= B.get(i);
              C.add((t+10)%10);
             if (t < 0) t = 1;
             else t = 0;
        }
        //去掉多余的零
        while(C.size() > 1 && C.get(C.size()-1) == 0 ) C.remove(C.size()-1);

        return C;
    }

    //该项用于检测两个数到底哪个大
    public static boolean cmp(List<Integer> A,List<Integer> B){
        if (A.size() != B.size()) return A.size() > B.size();
        for (int i = A.size() - 1; i >= 0; i--) {
            if (A.get(i) != B.get(i)) return A.get(i) > B.get(i);
        }
        return true;
    }
}