#include using namespace std; using ll = long long; using P = pair; #define fix(x) fixed << setprecision(x) #define asc(x) x, vector, greater #define rep(i, n) for(ll i = 0; i < n; i++) #define all(x) (x).begin(),(x).end() templatebool chmin(T&a, const T&b){if(a>b){a=b;return 1;}return 0;} templatebool chmax(T&a, const T&b){if(a> n >> p; q = p; vector a(n); rep(i,n) cin >> a[i]; sort(all(a)); while(q<=1e9){ map mp; rep(i,n){ ans += (mp[a[i]%q]++); } q *= p; } cout << ans << '\n'; return 0; }