#include <iostream>
#include <string>

const bool debugging = false;

const int size = 30;   // I want to make it easy to work with.
                       // Change to something big later.

struct bignum
{ 
  int digit[size];
  char sign;        // '+' or '-'
  bool ok;
};

   // to store the number one thousand six hundred and seventy nine,
   // 1679, digit[0]=9, digit[1]=7, digit[2]=6, digit[3]=1, all the rest are zero

void init(bignum & B)
{ for (int i = 0; i < size; i += 1)
    B.digit[i] = 0;
  B.sign = '+';
  B.ok = true; }

void print(bignum B)
{ if (! B.ok)
    cout << "BAD";
  cout << B.sign;
  bool printed = false;
  for (int i = size - 1; i >= 0; i -= 1)
  { int dig = B.digit[i];
    if (debugging)
      cout << "|";
    if (dig != 0 || printed || debugging)
    { cout << dig;
      printed = true; } }
  if (! printed)
    cout << "0"; }

void addsmall_is(bignum & B, int N)  // _is means "ignoring the + or - sign"
                                     // N must be small.
{ int toadd = N;
  int position = 0;
  while (toadd > 0)
  { int sum = B.digit[position] + toadd;
    if (sum < 10)
    { B.digit[position] = sum;
      toadd = 0; }
    else
    { B.digit[position] = sum % 10;
      toadd = sum / 10; }
    position += 1;
    if (position >= size)
    { B.ok = false;
      break; } } }

void main()
{ bignum X;
  init(X);
  while (true)
  { print(X);
    cout << "\n";
    char c;
    int n;
    cin >> c >> n;
    if (cin.fail())
      break;
    if (c == '+')
      addsmall_is(X, n);
    else
      cout << "+ is the only thing I know how to do\n"; } }