#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>

int main(int argc, char ** argv)
{
    if (argc != 3)
    {
        fprintf(stderr, "Usage: %s sentence init\n", argv[0]);
        return 1;
    }

    const char * sentence = argv[1];
    size_t init = strtoul(argv[2], NULL, 10);
    int count = 0;
    int toreach = -1;
    size_t len = strlen(sentence);

    if (init > len || sentence[init] != '(')
    {
        fprintf(stderr, "No opening parenthesis at index %zu\n", init);
        return 1;
    }

    for (size_t i = 0; i < len; ++i)
    {
        if (sentence[i] != '(' && sentence[i] != ')')
            continue;

        if (i == init)
            toreach = count;

        if (sentence[i] == '(')
            ++count;
        else if (sentence[i] == ')')
            --count;

        if (toreach == count)
        {
            printf("%s\n%*c %zu\n", sentence, (int)i+1, '\\', i);
            break;
        }
    }

    if (toreach != count)
    {
        fprintf(stderr, "No matching parenthesis found\n");
        return 1;
    }

    return 0;
}