#include #include #include #include #include #define maxn 15 using namespace std; const double eps=1e-7; int n; double l,r; double a[maxn]; double myabs(double now) { return now>0 ? now : -now; } double judge(double now) { double ans=0.0; for(int i=0;i<=n;i++) { ans+=a[i]*pow(now,i); } return ans; } int main() { scanf("%d%lf%lf",&n,&l,&r); for(int i=n;i>=0;i--) scanf("%lf",&a[i]); while(myabs(r-l)>=eps) { double mid1=l+((r-l)/3.0); double mid2=l+((r-l)/3.0*2.0); if(judge(mid1)>judge(mid2)) { r=mid2; } else l=mid1; } printf("%.5lf\n",l); }