Vector subscript out of range AND The application was unable to start correctly [c++]

I'm writing quite simple program in c++ using Visual Studio but i keep getting 2 errors and i could use some help.
One sometimes pops up when i run Local Windows Debugger after the app crashed and it says:
The application was unable to start correctly (0xc0000142)

message sometimes when running

And the second one i guess happens between after cin >> kwota;. Don't really know when though, because VS is not showing any exception. It's just a message box from the os. It says:
Debug Assertion Failed!
[...]
File: "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30133\include\vector"
Line: 1566
Expression: vector subscript out of range

message after puting second time into cin

Here you have my code. I got no idea what can cause it so any help would be great.

#include <iostream>
#include <vector>
#include <string>
#include <sstream>
#include <algorithm>

using namespace std;

int wyznaczZlote(vector<int> c, int z, int k)
{
    int nowakwota, pozycja, ilosc;
    if (z > k)
        return 0;

    for (int p = k/z; p >= 0; p--)
    {
        nowakwota = k % z;
        while (nowakwota > 0)
        {
            pozycja = c.size() - 1;
            while (c[pozycja] > nowakwota && pozycja >= 0)
            {
                pozycja--;
                if (pozycja < 0)
                    break;
            }
            if (pozycja < 0)
                break;
            ilosc = nowakwota / c[pozycja];
            nowakwota = nowakwota % c[pozycja];
        }

        if (nowakwota == 0)
            return p;
    }

    return -1;
}

int main()
{
    int ilecyna, ilezloto, kwota, liczbazlotych;
    vector<int> cyna;
    vector<int> zloto;
    string wejscie, wejscie2;

    cin >> ilecyna;
    cin.ignore();
    getline(cin, wejscie);

    stringstream wejscieStream(wejscie);
    int element;
    for (int i = 0; i < ilecyna; i++)
    {
        wejscieStream >> element;
        cyna.push_back(element);
    }
    sort(cyna.begin(), cyna.end());
    
    cin >> ilezloto;
    cin.ignore();
    getline(cin, wejscie2);

    stringstream wejscieStream2(wejscie2);
    for (int i = 0; i < ilecyna; i++)
    {
        wejscieStream2 >> element;
        cyna.push_back(element);
    }
    sort(zloto.begin(), zloto.end());

    cin >> kwota;

    liczbazlotych = wyznaczZlote(cyna, zloto[0], kwota);

    cout << '\n';

    if (liczbazlotych >= 0)
        cout << liczbazlotych << '\n';
    else
        cout << "NIE" << '\n';

    cin.ignore();
    getchar();
}

Thanks!

This sstatement

 cin >> wejscie;

inputs only one word as soon as a white space character is encountered.

So this for loop does not make a sense.

stringstream wejscieStream(wejscie);
int element;
for (int i = 0; i < ilecyna; i++)
{
    wejscieStream >> element;
    cyna.push_back(element);
}

Instead of using the operator >> in this statement

 cin >> wejscie;

it seems you need to use std::getline like

 std::getline( std::cin, wejscie );

But before using it you need to clear the input buffer like

#include <lomits>

//...

std::cin.ignore( std::numeric_limits<std::streamsize>::max(), '\n' );

Also this for loop

for (size_t p = k/z[0]; p >= 0; p--)

is an infinite for loop because the variable p having the unsigned integer type size_t never can be less than 0.

And this while loop is suspecious

        while (c[pozycja] > nowakwota)
            pozycja--;

because there is no check whether pozycja becomes less than 0.

And use English word as identifiers of variables. Otherwise your code will be unreadable for the most of users.

Also it is unclear why the second parameter denotes a vector

vector<int> z

while the only one its element z[0] is used within the function.