C :

#include "stdio.h"
#include "string.h"
int m,n;
char s[200000];
char a[201][11];
int d[201];
int f[200001];
void F(int x,int y)
{
	int i;
	if(x+d[y]>m)
		return;
	for(i=0;i<d[y];i++)
		if(s[x+i]!=a[y][i])
			return;
		f[x+d[y]]=1;
}
int main()
{
	int i,j;
	char c;
	scanf("%s",a[0]);
	d[0]=strlen(a[0]);
	n=0;
	while(a[n][0]!='.')
	{
		n++;
		scanf("%s",a[n]);
		d[n]=strlen(a[n]);	
	}
	m=0;
	while(~scanf("%c",&c))
	{
		if(c>='A'&&c<='Z')
		{
			s[m]=c;
			m++;
		}
	}
	s[m]=0;
	f[0]=1;
	for(i=0;i<m;i++)
	{
		if(f[i])
			for(j=0;j<n;j++)
				F(i,j);
	}
	for(i=m;i>=0;i--)
	{	
		if(f[i])
		{
			printf("%d\n",i);
			break;
		}
	}
	return 0;
}

C++ :

/*

PROB: prefix

LANG: C++

*/

#include <fstream>
#include<iostream>
using namespace std;
int main()
{

    //ifstream fin("prefix.in");

    //ofstream fout("prefix.out");

    string prim[201],str="",t;

    bool able[200001]={false};

    able[0]=true;

    int i,j,u,v,num=0;

    while(cin>>t&&t!=".") prim[num++]=t;

    while(cin>>t) str+=t;

    for(i=1;i<=str.size();i++)

    {

        for(j=0;j<num;j++)

        {

            if(prim[j].size()>i) continue;

            for(u=i-1,v=prim[j].size()-1;v>=0&&str[u]==prim[j][v];u--,v--);

            if(v<0&&able[i-prim[j].size()]) able[i]=true;

        }

    }

    for(i=str.size();!able[i];i--);

    cout<<i<<endl;

    return 0;

}

Pascal :

program p22830;
var a:array[0..203]of string;
    n,m,i,j,k,ans:longint;
    s:ansistring;
    st:string;
    f:array[0..200012]of boolean;
function jq(l,r:longint):string;
var i:longint;
begin
 i:=l;
 jq:='';
 while i<=r do
  begin
   jq:=jq+s[i];
   inc(i);
  end;
end;
begin
 i:=1;
 j:=1;
 readln(s);
 while s[1]<>'.'do
  begin
   while j<=length(s) do
    begin
     if s[j]<>' ' then a[i]:=a[i]+s[j]
     else inc(i);
     inc(j);
    end;
   readln(s);
   j:=1;inc(i);
  end;
 if a[i]='' then n:=i-1
 else n:=i;
 s:='';
 while not eof do
  begin
   readln(st);
   s:=s+st;
  end;
 fillchar(f,sizeof(f),false);
 f[0]:=true;
 for i:=1 to length(s) do
  for j:=1 to n do
   if (f[i]) then continue
   else if (i-length(a[j])>=0)and(f[i-length(a[j])])
           and(a[j]=jq(i-length(a[j])+1,i))
        then f[i]:=true;
 ans:=0;
 for i:=0 to length(s) do
 if f[i] then ans:=i;
 writeln(ans);
end.