#include<iostream>
using namespace std;
int main(){
    double mass, velocity;
    cin>>mass;
    cin>>velocity;
    if(mass<0 || velocity<0){
        cout<<"Invalid input";
        retturn 0;
    }
    double kineticEnergy = 0.5 * mass * velocity * velocity;
    cout<<kineticEnergy;
    return 0;
}