#include <bits/stdc++.h>
#define boAshraf ios_base::sync_with_stdio(false); cin.tie(NULL);
#define ll long long
#define sz(s) (int)(s).size()
#define all(s) (s).begin(),(s).end()
using namespace std;
void File();
void sol();
typedef long double ld;
typedef complex<double> point;
template<class T>
istream& operator>>(istream& is, complex<T>& p) {
    T value;
    is >> value;
    p.real(value);
    is >> value;
    p.imag(value);
    return is;
}
#define PI acos(-1.0)
#define EPS 1e-8
#define X real()
#define Y imag()
#define angle(a)  (atan2((a).imag(), (a).real()))
#define length(a)   (hypot((a).imag(), (a).real()))
#define vec(a,b)  ((b)-(a))
#define dp(a,b)   ( (conj(a)*(b)).real() )
#define cp(a,b)   ( (conj(a)*(b)).imag() )
#define normalize(a)(a)/length(a)
bool same(point p1, point p2) {
    return dp(vec(p1, p2), vec(p1, p2)) < EPS;
}
point rotate(point p, double angle, point around = point(0, 0)) {
    p -= around;
    return (p * exp(point(0, angle))) + around;
}
int main() {
    boAshraf
    File();
    int t = 1;
//    cin >> t;
    while (t--) {
        sol();
    }
    return 0;
}

void sol() {
    point p(0,0);
    int n;
    cin>>n;
    while(n--){
        double ang;
        int d;
        cin>>ang>>d;
        ang*=PI/180;
        point p2(d*cos(ang),d*sin(ang));
        p+=p2;
    }
    cout<<fixed<<setprecision(8)<<length(p)<<'\n';
}

void File() {
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
}