#include <iostream>
#include <iomanip>
#include <cmath>
#define PI 3.14159
using namespace std;

int main()
{
    double x1,y1,x2,y2,x3,y3;
    double d,a,b,c;

    while(cin>>x1>>y1>>x2>>y2>>x3>>y3)
    {
        a=sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
        b=sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));
        c=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
        d=acos(((a*a)+(c*c)-(b*b))/(2*a*c));
        cout <<setiosflags(ios::fixed)<<setprecision(2);
        cout <<d*180/PI<<endl;
    }

    return 0;

}