#include <iostream>
#include <math.h>
using namespace std;
 
 int main() {
   int n;
   double a, sum = 0;
   double period = 2*M_PI;
   cin >> n;
 
   for(int i=0; i<n; i++)
   {
      cin >> a;
      sum += a;
 
      if ( fabs ( sum ) >= period )
      {
         sum = fmod( sum, period );
      }
   }
   cout << sin ( fabs ( sum )) ;
   return 0;
}