// zadanie 1.
#include <iostream>

using namespace std;

string wstaw(const string src, const char s, size_t p)
{
    string dest = "";
    for(unsigned i = 0; i < p; ++i)
        dest += src[i];
    dest += s;
    unsigned n = src.size();
    for(unsigned i = p; i < n; ++i)
        dest += src[i];
    return dest;
}

int main()
{
    string napis = "jakis napis";
    cout << wstaw(napis, 'a', 3);
    return 0;
}