How do I fix this code in c++?

I'm a beginner in C++ and I wrote a simple program to study the syntax of C++. The code is going to a response but is wrong. The code is:

// converter_temp1.cpp
// converter 3 temp. celsius, fahrenheit e kelvin

// entrar: temperatura, escala atual e pretendida

#include "stdafx.h"


int main()
{
    double t, tempC, tempF, tempk;

    std::string sa, sp, cel, fah, kel;

    std::cout << "Enter with your temperature, actual and pretend scale, for celsius = cel, fahrenheit = fah and kelvin = kel" << std::endl;
    std::cin >> t >> sa >> sp;

    if (sa == cel && sp == fah) {
        tempF = 32 + (9 * t) / 5;
        std::cout << ">>>> Temperature is " << tempF << " F in Fahrenheit!!!! <<<<" << std::endl;

    }else {
        if (sa == kel && sp == cel) {
            tempC = t + 273;
            std::cout << ">>>> Temperature is " << tempC << " C in Celsius!!!! <<<<" << std::endl;

        }
        else {
            std::cout << ">>>> Temperature scale wrong!!!! <<<<" << std::endl;
        }
    }

    return 0;
}

The answer of this code is always >>>> Temperature scale wrong!!!! <<<<. Could anyone help me?

Thanks!