我表示30+行过的没用
program P1318;
var
s,t,w,i,j,k:integer;
a:string;
b:string;
begin
readln(s,t,w);
readln(a);
for i:=1 to 5 do
for j:=w downto 1 do
if ord(a[j])-96<(t-w+j) then
begin
b:=copy(a,1,j-1)+succ(a[j]);
for k:=j+1 to w do
b:=b+succ(b[k-1]);
a:=b;
writeln(a);
b:='';
break;
end;

end.