Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:63:27: error: ‘u’ was not declared in this scope st[1] = 1; st[2] = 2; u = 2; ^ user.cpp:64:5: error: ‘vis’ was not declared in this scope vis[2] = true; ^ user.cpp:71:60: error: ‘cross_product’ was not declared in this scope while (u >= 2 && cross_product(v[st[u-1]], v[st[u]], v[i]) < EPS) ^ user.cpp:72:20: error: ‘head’ was not declared in this scope vis[st[head--]] = false; ^ user.cpp:74:8: error: ‘head’ was not declared in this scope st[++head] = i; ^