#include <iostream>
#include <cmath>

using namespace std;

int main() {
    double l = 0;
    double r = 2;

    while ( r - l > 0.0000001 ) {
        double m = (l+r)/2;
        if ( m - cos(m) > 0 )
            r = m;
        else
            l = m;
    }
    cout << l << endl;
    return 0;
}