本人比较nc，看不出问题。。。
附上代码：
program rqnoj518;
var
a:array[65..90] of char;
b,c:array[1..100] of char;
i,j,k:longint;
m:boolean;
begin
for i:=65 to 90 do a[i]:=' ';
for i:=1 to 100 do begin
read(b[i]);
if b[i]=#13 then begin
k:=i-1;
readln;
break;
end;
end;
for i:=1 to k do read(c[i]);
readln;
for i:=1 to k do begin
if ((a[ord(b[i])]=' ') or (a[ord(b[i])]=c[i])) then begin
a[ord(b[i])]:=c[i];
end
else begin
write('Failed');
halt;
end;
end;
for i:=65 to 89 do begin
for j:=i+1 to 90 do begin
if a[i]=a[j] then begin
write('Failed');
halt;
end;
end;
end;
for i:=65 to 90 do begin
if a[i]=' ' then begin
write('Failed');
halt;
end;
end;
for i :=1 to 100 do begin
read(b[i]);
if b[i]=#13 then begin
k:=i-1;
break;
end;
end;
for i:=1 to k do begin
write(a[ord(b[i])]);
end;
end.