import std.stdio,
       std.conv,
       std.string,
       std.range,
       std.algorithm;

void main()
{
    auto input = readln.split.to!(int[]);
    auto N = input[0], K = input[1];
    auto S = readln.strip;

    int count;
    size_t index;
    if (S[K - 1] == '(')
    {
        foreach (i, e; S[K - 1 .. $])
        {
            count += (e == '(' ? 1 : -1);

            if (count == 0)
            {
                index = K + i;
                break;
            }
        }
    }
    else
    {
        foreach_reverse (i, e; S[0 .. K])
        {
            count += (e == ')' ? 1 : -1);

            if (count == 0)
            {
                index = i + 1;
                break;
            }
        }
    }
    index.writeln;
}