#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  int n, s, k;
  cin >> n >> s >> k;
  vector<int> a(n);
  rep(i, n) cin >> a[i];
  pair<int, int> ans = { 1e9, -1 };
  rep(i, n) {
    int diff = abs(a[i] - s);
    if (diff <= k) {
      if (ans.first > diff) ans = { diff, i + 1 };
    }
  }
  if (ans.second == -1) {
    cout << "Unlucky!" << endl;
  }
  else {
    cout << ans.second << endl;
  }
  return 0;
}