index_of

#include <iostream>
#include <vector>

using namespace std;

vector<int> passing_Input(vector<int> & vec, int size_vec);
int find_Element (int equal_element, vector<int> & vec);

int main()
{
    int size = 0;
    vector<int> myvec;

    passing_Input(myvec,size);

    int printElement = 0;
    cin>>printElement;


    int res =  find_Element(printElement,myvec);

    cout<<res;


    return 0;
}


vector<int> passing_Input(vector<int> & vec, int size_vec)
{
    cin>>size_vec;

    for(int i = 0; i < size_vec; i++)
    {
        int element;
        cin>>element;
        vec.push_back(element);
    }

    return vec;

}

int find_Element (int equal_element,vector<int> & v)
{
    int size_vec = v.size();
    int result = 0;
    bool find_element = false;

    for(int i = 0; i < size_vec; i++)
    {
        if(v[i] == equal_element)
        {
           result = i;
           find_element = true;

        }
    }

    if(find_element == 0)
    {
        result =-1;
    }


    return result;
}