#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

const double IZP_E = 2.7182818284590452354;        // e
const double IZP_PI = 3.14159265358979323846;      // pi
const double IZP_2PI = 6.28318530717958647692;     // 2*pi
const double IZP_PI_2 = 1.57079632679489661923;    // pi/2
const double IZP_PI_4 = 0.78539816339744830962;    // pi/4

double sigdig=0.001;
double vstup=2.71;
double sih=0;
double coh=0;
float tnh=0;
double starycoh=0;
double dalsicoh=0;
double starysih=0;
double dalsisih=0;
double s=0;
double exponent;
double moc;
double f=1;
double n;


double mocnina(double vstup, double s){
    moc=1;
    for(n=0; n<s; n++){
    moc=moc*vstup;
    }
    return(moc);
}

double absol(double x, double y){
    return(x-y<0)?y-x: x-y;
}

double fakt(double z){
    for(; n>0; n--){
        f=f*n;
    }
    return(f);
}

double sinush(double vstup){
    s=1;
    starysih=(vstup/(fakt(s)));
    do{
        s=s+2;
        dalsisih=((mocnina(vstup, s))/(fakt(s)));
        sih=starysih+dalsisih;
    }while((absol(starysih, sih))<sigdig);
    return(sih);
}

double cosinush(double vstup){
    s=0;
    starycoh=1;
    do{
        s=s+2;
        starycoh=coh;
        dalsicoh=((mocnina(vstup, s))/(fakt(s)));
        coh=starycoh+dalsicoh;
    }while((starycoh-coh)<sigdig);
    return(coh);
}

int hypertan(){
        sinush(vstup);
        cosinush(vstup);
        tnh=sih/coh;
    printf("%.10e\n", tnh);
return(0);
}

int main()
{
    hypertan();
    return(0);
}