#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main() {
vector<int> v = { 7, 3, 6, 2, 6 };
int key = 6;
vector<int>::iterator itr = find(v.begin(), v.end(), key);
int index = distance(v.begin(), itr);
cout << index << endl;
return 0;
}