#include #define EPS 1e-9 #define INF 1070000000LL #define MOD 1000000007LL #define fir first #define foreach(it,X) for(auto it=(X).begin();it!=(X).end();it++) #define numa(x,a) for(auto x: a) #define ite iterator #define mp make_pair #define rep(i,n) rep2(i,0,n) #define rep2(i,m,n) for(int i=m;i<(n);i++) #define pb push_back #define pf push_front #define sec second #define sz(x) ((int)(x).size()) #define ALL( c ) (c).begin(), (c).end() #define gcd(a,b) __gcd(a,b) #define mem(x,n) memset(x,n,sizeof(x)) #define endl "\n" using namespace std; template void deploy(std::ostream &os, const TUPLE &tuple){} template void deploy(std::ostream &os, const TUPLE &t){ os << (POS == 0 ? "" : ", ") << get(t); deploy(os, t); } template std::ostream& operator<<(std::ostream &os, std::pair &p){ os << "(" << p.first <<", " << p.second <<")";return os; } template std::ostream& operator<<(std::ostream &os, std::vector &v){ int remain = v.size(); os << "{"; for(auto e: v) os << e << (--remain == 0 ? "}" : ", "); return os; } template std::ostream& operator<<(std::ostream &os, std::set &v){ int remain = v.size(); os << "{"; for(auto e: v) os << e << (--remain == 0 ? "}" : ", "); return os; } template std::ostream& operator<<(std::ostream &os, std::map &mp){ int remain = mp.size(); os << "{"; for(auto e: mp) os << "(" << e.first << " -> " << e.second << ")" << (--remain == 0 ? "}" : ", "); return os; } #define DEBUG1(var0) { std::cerr << (#var0) << "=" << (var0) << endl; } #define DEBUG2(var0, var1) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG1(var1); } #define DEBUG3(var0, var1, var2) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG2(var1,var2); } #define DEBUG4(var0, var1, var2, var3) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG3(var1,var2,var3); } using ll = long long; template std::vector GaussianElimination(std::vector > A,std::vector b){ bool used[A.size()]; for (int i = 0; i < A.size();i++) { used[i] = false; } for (int i = 0; i < A.size(); i++) { int nowp = 0; for (int i2 = 0; i2 < A.size(); i2++) { if (!used[i2] && A[i2][i] != 0) { nowp = i2; used[nowp] = true; break; } } T a = A[nowp][i]; A[nowp][i] = 1; b[nowp] /= a; for (int j = i + 1; j < A.size(); j++) { A[nowp][j] /= a; } for (int i2 = 0; i2 < A.size(); i2++) { if (nowp == i2) { continue; } T p = A[i2][i]; A[i2][i] = 0; for (int j = i+1;j < A.size();j++) { A[i2][j] -= p * A[nowp][j]; } b[i2] -= p * b[nowp]; } //DEBUG1(A); //DEBUG1(b); } /* rep(i,sz(A)){ rep(j,sz(A)){ cout << A[i][j] << " "; } cout << endl; } */ return b; } int main() { cin.tie(0); ios_base::sync_with_stdio(0); int N; cin >> N; vector nums(N); vector > A(N,vector (N,1)); rep(i,N){ cin >> nums[i]; A[i][i] = 0; } vector x = GaussianElimination(A,nums); //DEBUG1(x) cout << count(ALL(x),2.0) << " " << count(ALL(x),4.0) << endl; return 0; }