C++ :

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
using namespace std;
int main ()
{
 char a1[10001],b1[10001];
 int a[10000],b[10000],c[10000],l1,l2,l,i,m;
 memset(a,0,sizeof(a));
 memset(b,0,sizeof(b));
 memset(c,0,sizeof(c));
 cin.getline(a1,10000);cin.getline(b1,10000);
 l1=strlen(a1);l2=strlen(b1);
 for (i=0;i<=l1-1;++i)
  a[l1-i]=a1[i]-48;
 for (i=0;i<=l2-1;++i)
  b[l2-i]=b1[i]-48;
 l=1;m=0;
 while ((l<=l1)||(l<=l2))
  {
   c[l]=a[l]+b[l]+m;
   m=c[l]/10;
   c[l]%=10;
   l++;
  }
 c[l]=m;
 if (c[l]==0) l=l-1;
 for (i=l;i>=1;i--)
  cout<<c[i];
 return 0;
}

Pascal :

var
c,d,k:string;
m,s,i,n,y:integer;
a,b,e:array[1..250] of integer;
w:boolean;
begin
    readln(c);
    readln(d);
    for i:=1 to length(c) do
    begin
    k:=copy(c,i,1);
    a[250-length(c)+i]:=ord(k[1])-48;
    end;
    for i:=1 to length(d) do
    begin
    k:=copy(d,i,1);
    b[250-length(d)+i]:=ord(k[1])-48;
    end;

    for i:=250 downto 1 do
   e[i]:=a[i]+b[i];

  for i:=250 downto 1 do
  if e[i]>9 then
  begin
    e[i]:=e[i] mod 10;
    e[i-1]:=e[i-1]+1;
  end;

  w:=false;
  for i:=1 to 250 do
  if (e[i]>0) or (w=true) then begin write(e[i]);w:=true;end;

    end.