#include <bits/stdc++.h> using namespace std; long long mod = 998244353; //入力が必ず-mod<a<modの時. struct mint{ long long v = 0; mint(){} mint(int a){v = a<0?a+mod:a;} mint(long long a){v = a<0?a+mod:a;} mint(unsigned long long a){v = a;} long long val(){return v;} void modu(){v %= mod;} mint repeat2mint(const long long a,long long b){ mint ret = 1,p = a; while(b){ if(b&1) ret *= p; p *= p; b >>= 1; } return ret; }; mint &operator=(const mint &b) = default; mint operator-() const {return mint(0)-(*this);} mint operator+(const mint b){return mint(v)+=b;} mint operator-(const mint b){return mint(v)-=b;} mint operator*(const mint b){return mint(v)*=b;} mint operator/(const mint b){return mint(v)/=b;} mint operator+=(const mint b){ v += b.v; if(v >= mod) v -= mod; return *this; } mint operator-=(const mint b){ v -= b.v; if(v < 0) v += mod; return *this; } mint operator*=(const mint b){v = v*b.v%mod; return *this;} mint operator/=(mint b){ if(b == 0) assert(false); int left = mod-2; while(left){if(left&1) *this *= b; b *= b; left >>= 1;} return *this; } mint operator++(int){*this += 1; return *this;} mint operator--(int){*this -= 1; return *this;} bool operator==(const mint b){return v == b.v;} bool operator!=(const mint b){return v != b.v;} bool operator>(const mint b){return v > b.v;} bool operator>=(const mint b){return v >= b.v;} bool operator<(const mint b){return v < b.v;} bool operator<=(const mint b){return v <= b.v;} mint pow(const long long x){return repeat2mint(v,x);} mint inv(){return mint(1)/v;} }; int main(){ ios_base::sync_with_stdio(false); cin.tie(nullptr); int T; cin >> T; while(T--){ long long N,K; cin >> N >> K; vector<long long> A; long long ok = 0,sum = 0; while(N--){ long long a; cin >> a; if(a == 0) continue; a %= K; sum += a; if(a) A.push_back(a); else ok++; } N = A.size(); if(N == 0){cout << "0\n"; continue;} if(sum%K){cout << "-1\n"; continue;} long long answer = 1e18; for(int t=0; t<=min(K-1,ok); t++){ vector<long long> C(K+1); for(auto &a : A) C.at(a)++; C.at(K) = t; priority_queue<long long,vector<long long>,greater<>> Q; long long zero = 0; for(int i=K; i>=0; i--) while(C.at(i)--){ long long now = zero+i; Q.push(now); if(Q.size() == K){ long long left = Q.top()-zero; zero += left; while(Q.size() && Q.top() == zero) Q.pop(); } } if(Q.size()) continue; answer = min(answer,zero); } if(answer > 9e17) answer = -1; cout << answer << "\n"; } }