char temp;

temp = *x;

*x = *y;

*y = temp;

if (l==r) {

printf("%s\n", str);

} else {

for (int i=1; i<=r; i++) [

swap((str+l), (str+i));

permutation(str, l+1, r);

swap((str+l), (str+i)); // backtrack

]

}

{

if (k == 0)

{

printf("%s\n", combinationStack);

return;

}

for (int i = offset; i <= length - k; ++i)

{

push(str[i]);

combination(str, length, i+1, k-1);

pop();

}

{

int N, K, T;

char str[MAX_STRING_LENGTH];

scanf("%d", &T);

for (int test_case = 1; test_case <= T; test_case++)

{

scanf("%s%d%d", str, &N, &K);

str[N] = 0;

printf("#%d\n", test_case);

permutation(str, 0, N-1);

combination(str, N, 0, K);

}

return 0;

}