#include <stdio.h>
#include <math.h>
double t0=1.0, T=3.0, h;
double f(double t,double y){
    return -y/t+2*sqrt(y/t)*cos(t);
}
double rk(double t,double y){
    double k1=f(t,y);
    double k2=f(t+h/2,y+h*k1/2);
    double k3=f(t+h/2,y+h*k2/2);
    double k4=f(t+h,y+h*k3);
    return h*(k1+2*(k2+k3)+k4)/6;
}
int main(){
    double Y3=sin(T)*sin(T)/T;
    for(int n=10;n<10000;n*=2){
        double y=sin(1.0)*sin(1.0);
        h=(T-t0)/n;
        for(int i=0;i<n;i++){
            double t=t0+i*h;
            y+=rk(t,y);
        }
        printf("%d %24.15e\n",n,fabs(y-Y3));
    }
    return 0;
}