#if !__INCLUDE_LEVEL__ #include __FILE__ int main() { ll N,M;cin >> N >> M; vl A(N);rep(i,N)cin >> A[i]; if(M==1){ cout << 1 << endl; exit(0); } rep(i,N)A[i] = A[i]%M; sort(all(A)); ll ans = 0; unordered_map Mo; fore(a,A)Mo[a]+=1; unordered_map seen; fore(a,A){ if(seen[a]==0){ if(2*a==M || a==0){ seen[a]=1; ans += 1; } else{ seen[a]=1; seen[M-a]=1; ans += max(Mo[a],Mo[M-a]); } //cout << a << " " << ans << endl; } } cout << ans << endl; } #else #include #include using namespace std; using namespace atcoder; #define rep(i, n) for(int i = 0; i < n; i++) #define rrep(i, n) for(int i = n-1; i >= 0; i--) #define range(i, m, n) for(int i = m; i < n; i++) #define fore(i,a) for(auto &i:a) #define all(v) v.begin(), v.end() #define rall(v) v.rbegin(), v.rend() #define Sum(v) accumulate(all(v),0) #define minv(v) *min_element(all(v)) #define maxv(v) *max_element(all(v)) typedef long long ll; typedef vector vl; typedef vector> vvl; const ll INF = 1e16; const ll MOD1 = 1000000007; const ll MOD2 = 998244353; template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } ll SN(char s){return ll(s-'0');} ll SN(string s){return stoll(s);} int alpN(char s){return int(s-'a');} int AlpN(char s){return int(s-'A');} using Graph = vector>; using GraphCost = vector>>; using mint1 = modint1000000007; using mint2 = modint998244353; using pll = pair; template ostream &operator<<(ostream &o,const vector&v){for(int i=0;i<(int)v.size();i++)o<<(i>0?" ":"")< bool contain(const std::string& s, const T& v) { return s.find(v) != std::string::npos; } #endif