793A

#include<iostream>#include<vector>#include<string>#include<set>#include<map>#include<algorithm>#include<queue>#include<list>#include<stack>#include<cstdio>#include<fstream>#include<numeric>#include<functional>#include<utility>#include<memory>using namespace std;using namespace placeholders;typedef long long int ll;int main(){ll n, k;while (cin >> n >> k){vector<ll> price;ll min_p = INT_MAX;for (ll i = 0; i < n; i++){ll temp;cin >> temp;price.push_back(temp);if (temp < min_p) min_p = temp;}ll res = 0;for (int i = 0; i < n; i++){if ((price[i] - min_p) % k){res = -1;break;}else{res += ((price[i] - min_p) / k);}}cout << res << endl;}//system("pause");return 0;}