大整数 Bignumber

#include <bits/stdc++.h>
using namespace std;

struct big_number {
  bool is_postive;
  string s;
  big_number () {}
  big_number (string ss) { if (ss[0] != '-') {this->s = ss; this->is_postive = true;} else {this->s = ss.substr(1, ss.size()); this->is_postive = false;}}
  big_number (string ss, bool flag) {this->s = ss; this->is_postive = flag; }
  void print() {if (is_postive == false) cout << "-"; cout << s;}
  void println() {if (is_postive == false) cout << "-"; cout << s << "\n";}
  int size() { return int(s.size()); }
  bool operator < (const big_number &b) const {
    if (int(s.size()) != int(b.s.size())) return int(s.size()) < int(b.s.size());
    return s < b.s;
  }
  bool operator > (const big_number &b) const {
    if (int(s.size()) != int(b.s.size())) return int(s.size()) > int(b.s.size());
    return s > b.s;
  }
  bool operator == (const big_number &b) const {
    return s == b.s;
  }
  bool operator != (const big_number &b) const {
    return s != b.s;
  }
  friend inline big_number operator + (const big_number &p, const big_number &q) {
    if (p.is_postive != q.is_postive) {
      if (p.is_postive == false) {big_number np(p.s, true), nq(q.s, true); return nq - np;}
      else {big_number np(p.s, true), nq(q.s, true); return np - nq;}
    } 
    string a = p.s, b = q.s;
    reverse(a.begin(), a.end()); reverse(b.begin(), b.end()); 
    if (int(a.size()) < int(b.size())) swap(a, b); // len(a) > len(b)
    int t = 0; big_number ans;
    for (int i = 0; i < int(a.size()); i ++ ) {
      if (i < int(a.size())) t += (a[i] - '0');
      if (i < int(b.size())) t += (b[i] - '0');
      ans.s += char('0' + (t % 10)); t /= 10;
    }
    if (t) ans.s += char('0' + (t % 10));
    reverse(ans.s.begin(), ans.s.end());
    if (p.is_postive == false and q.is_postive == false) ans.is_postive = false;
    else ans.is_postive = true;
    return ans;
  }

  friend inline big_number operator - (const big_number &p, const big_number &q) {
    if (p.is_postive != q.is_postive) {
      if (p.is_postive == false) {big_number np(p.s, false), nq(q.s, false); return nq + np;}
      else {big_number np(p.s, true), nq(q.s, true); return np + nq;}
    } else {
      if (p.is_postive == false) {big_number np(p.s, true), nq(q.s, true); return nq - np;}
    }
    string a = p.s, b = q.s;
    if (a == b) return big_number("0");
    reverse(a.begin(), a.end()); reverse(b.begin(), b.end()); 
    // bool postive = true;
    int t = 0; big_number ans;
    if (p < q) {swap(a, b); ans.is_postive = false; } // len(a) > len(b)
    for (int i = 0; i < int(a.size()); i ++ ) {
      if (i < int(a.size())) t += (a[i] - '0');
      if (i < int(b.size())) t -= (b[i] - '0');
      ans.s += char('0' + ((t + 10) % 10)); 
      t = t < 0 ? -1 : 0;
    }
    assert(t == 0);
    while (not ans.s.empty() and ans.s.back() == '0') ans.s.pop_back();
    reverse(ans.s.begin(), ans.s.end());
    return ans;
  }

  string MUL (string a, int b, int cnt) const {
    string B = a, ans; int n = B.size();
    int t = 0; reverse(B.begin(), B.end());
    if (cnt) ans += string(cnt, '0');
    for (int i = 0; i < n; i ++ ) {
      t += b * int(B[i] - '0');
      ans += char('0' + (t % 10));
      t /= 10;
    }
    while (t) {ans += char('0' + (t % 10)); t /= 10; }
    reverse(ans.begin(), ans.end());
    return ans;
  }

  friend inline big_number operator * (const big_number &p, const big_number &q) {
    string a = p.s, b = q.s;
    
    if (int(a.size()) < int(b.size())) swap(a, b); // len(a) > len(b)
    big_number ans("0"), mul(a);
    reverse(b.begin(), b.end());
    for (int i = 0; i < int(b.size()); i ++ ) {
      string now = p.MUL(a, int(b[i] - '0'), i);
      ans = ans + big_number(now);
    }
    if (p.is_postive != q.is_postive) ans.is_postive = false;
    else ans.is_postive = true;
    return ans;
  }
};

int main() {
  // big_number a("1231"), b("234");
  string x, y; cin >> x >> y;
  big_number a(x), b(y), ans;
  ans = a + b; ans.println();
  ans = a - b; ans.println();
  ans = a * b; ans.println();
  ans = b - a; ans.println();
  ans = (b - a) * (a - b); ans.println();

  
  return 0;
}