#include <string>
#include <iostream>
#include <fstream>

using namespace std;

struct atom
{ string symbol, name;
  int atno;
  double atwt; };

void print(atom a)
{ cout << "Name: " << a.name << "\n"
       << "Symbol: " << a.symbol << "\n"
       << "atwt: " << a.atwt << "\n"
       << "atno: " << a.atno << "\n"; }

bool lookup(atom table[], int N,
            string wanted,
            atom & result)
{ int pos = 0;
  while (pos < N)
  { if (table[pos].symbol == wanted)
    { result = table[pos];
      return true; }
    pos += 1; }
  return false; }

struct type
{ char what;
  string symbol;
  int value; };

type classify(string x)
{ type result;
  result.value = 0;
  for (int i = 0; i < x.length(); i += 1)
    if (x[i] < '0' || x[i] > '9')
    { result.what = 'S';
      result.symbol = x;
      return result; }
    else
      result.value = result.value * 10 + x[i] - '0';
  result.what = 'N';
  return result; }

int main()
{ atom table[120];

  ifstream elf;
  elf.open("new.txt");
  if (elf.fail())
  { cout << "Can't open the file\n";
    exit(1); }

  int pos = 0;
  while (true)
  { elf >> table[pos].symbol
        >> table[pos].name 
        >> table[pos].atno
        >> table[pos].atwt;
    if (elf.fail())
      break;
    pos += 1; }
  elf.close();

  double molwt = 0.0, last_atwt = 0.0;
  while (true)
  { string wanted;
    cout << "Enter a symbol: ";
    cin >> wanted;
    if (cin.fail())
      break;

    type t = classify(wanted);
    if (t.what == 'N')
    { cout << "The number " << t.value << "\n";
      molwt += (t.value-1) * last_atwt; }
    else
    { atom x;
      bool ok = lookup(table, pos, wanted, x);
      if (ok)
      { print(x);
        molwt += x.atwt;
        last_atwt = x.atwt; }
      else
        cout << wanted << " not found\n"; } }
  cout << "\nMolecular weight = " << molwt << "\n"; }