C++ :

#include <iostream>
#include <algorithm>
#include <string>
#include <sstream>
#include <cstring>
#include <stack>
using namespace std;

const int N = 27, MOD = 0x7fffffff;
long long Std_Value[N], v[N];
string s;
istringstream ss;

struct State
{
	long long v, c1, c2;
	char c3;
	
	State() {}
	State(long long V, long long C1, long long C2, char C3) {v = V; c1 = C1; c2 = C2; c3 = C3;}
} C;
stack<State> st[N];
long long Pow(long long a, int b)
{
	long long c = 1;
	while (b)
	{
		if (b & 1) c = c * a % MOD;
		a = a * a % MOD;
		b >>= 1;
	}
	return c;
}
void Calc()
{
	int i, c4;
	long long c1[N], c2[N] = {0};
	char c, c3[N];
	
	fill(c1, c1 + N, 1);
	fill(v, v + N, 0);
	fill(c3, c3 + N, '+');
	ss.str(s);
	while (ss >> c)
	{
		if (c == '^') ss >> c4;
		for (i = 0; i < N; i++)
			switch (c)
			{
				case '(': 
					st[i].push(State(v[i], c1[i], c2[i], c3[i]));
					v[i] = c2[i] = 0; c1[i] = 1; c3[i] = '+';
					break;
				case ')':
					C = st[i].top(); st[i].pop();
					if (c3[i] == '+') c2[i] = (v[i] + c1[i] * c2[i] % MOD) % MOD;
					else c2[i] = (v[i] - c1[i] * c2[i] % MOD) % MOD;
					c1[i] = C.c1; c3[i] = C.c3; v[i] = C.v;
					break;
				case '+':
				case '-':
					if (c3[i] == '+') v[i] = (v[i] + c1[i] * c2[i] % MOD) % MOD;
					else v[i] = (v[i] - c1[i] * c2[i] % MOD) % MOD;
					c1[i] = 1; c2[i] = 0; c3[i] = c; break;
				case '*': c1[i] = c1[i] * c2[i] % MOD; c2[i] = 0; break;
				case '^': c2[i] = Pow(c2[i], c4); break;
				case 'a': c2[i] = i; break;
				default: c2[i] = c2[i] * 10 + c - '0';
			}
	}
	for (i = 0; i < N; ++i)
		if (c3[i] == '+') v[i] = (v[i] + c1[i] * c2[i] % MOD) % MOD;
		else v[i] = (v[i] - c1[i] * c2[i] % MOD) % MOD;
	ss.clear();
}

int main()
{
	int n, i, j;
	bool OK;
	
	getline(cin, s);
	Calc();
	copy(v, v + N, Std_Value);
	getline(cin, s);
	ss.str(s);
	ss >> n;
	ss.clear();
	for (i = 0; i < n; ++i)
	{
		getline(cin, s);
		Calc();
		OK = true;
		for (j = 0; j < N; ++j)
			if ((Std_Value[j] - v[j]) % MOD) {OK = false; break;}
		if (OK) cout << (char)(i + 'A');
	}
	cout << endl;
	
	return 0;
}

Pascal :

var
  s:string;
  h:array[1..100] of int64;
  i,kk:longint;
  ans,n,base,m,p:int64;
function power(x:int64; y:longint):int64;
var
  i:longint;
begin
  x:=x mod maxlongint;
  power:=1;
  for i:=1 to y do power:=power*x mod maxlongint;
end;
function data(l,r:longint):int64;
var
  i:longint;
begin
  data:=0;
  for i:=l to r do data:=data*10+ord(s[i])-48;
end;
function find(l,r:longint):int64;
var
  i,min:longint;
begin
  min:=maxlongint;
  find:=0;
  for i:=r downto l do
    if h[i]<min then
    begin
      min:=h[i];
      find:=i;
    end;
end;
function opt(a,k,b:int64):int64;
begin
  case s[k] of
    '+':opt:=(a+b) mod maxlongint;
    '-':opt:=(a-b) mod maxlongint;
    '*':opt:=(a*b) mod maxlongint;
    '^':opt:=power(a,b) mod maxlongint;
  end;
end;
function work(l,r:longint):int64;
var
  a,b:int64;
  k:longint;
begin
  if s[l]='(' then inc(l);
  if s[r]=')' then dec(r);
  k:=find(l,r);
  if k=0 then exit(data(l,r));
  a:=work(l,k-1);
  b:=work(k+1,r);
  work:=opt(a,k,b);
end;
begin
  readln(s);
  p:=pos(' ',s);
  while p<>0 do
  begin
    delete(s,p,1);
    p:=pos(' ',s);
  end;
  n:=length(s);
  for i:=1 to n do
    if s[i]='a' then s[i]:='2';
  for i:=1 to n do h[i]:=maxlongint;
  base:=0;
  for i:=1 to n do
    case s[i] of
      '(':inc(base,3);
      ')':dec(base,3);
      '+','-':h[i]:=base+1;
      '*','/':h[i]:=base+2;
      '^':h[i]:=base+3;
    end;
  ans:=work(1,n) mod maxlongint;
  readln(m);
  for kk:=1 to m do
  begin
    readln(s);
    p:=pos(' ',s);
    while p<>0 do
    begin
      delete(s,p,1);
      p:=pos(' ',s);
    end;
    n:=length(s);
    for i:=1 to n do
      if s[i]='a' then s[i]:='2';
    for i:=1 to n do h[i]:=maxlongint;
    base:=0;
    for i:=1 to n do
      case s[i] of
        '(':inc(base,3);
        ')':dec(base,3);
        '+','-':h[i]:=base+1;
        '*','/':h[i]:=base+2;
        '^':h[i]:=base+3;
      end;
    if ans=work(1,n) mod maxlongint then write(chr(64+kk));
  end;
end.