v3

#include <iostream>
#include <iomanip>
#include <cmath>

#define ABS(x) ((x) < 0 ? -(x) : (x))

int main() {
    // Input
    double a, p, epsilon;
    std::cout << "Enter root-value: ";
    std::cin >> a;
    std::cout << "Enter root-power: ";
    std::cin >> p;
    std::cout << "Enter epsilon: ";
    std::cin >> epsilon;

    // Variables init
    double prev = a;
    bool exit = false;
    unsigned long long iterations = 0;

    while (true) {
        // Count
        double v = 1 / p * ((p - 1)*prev + a / (pow(prev, p - 1)));
        iterations++;

        // Count delta, output
        double delta = ABS(v - prev);
        prev = v;                    // Save current value
        std::cout << "Iteration: " << std::setw(8) << iterations
            << "; Value: " << std::setw(8) << v
            << " ; Delta: " << std::setw(8) << delta
            << std::endl;
        if (delta <= epsilon)
            break;
    }

    // Output
    double accurate = pow(a, 1 / p);
    std::cout << "Accurate value: " << accurate << std::endl;
    if (accurate > prev) {
        std::cout << "Accurate bigger on: " << accurate - prev << std::endl;
    }
    else if (accurate < prev) {
        std::cout << "Accurate smaller on: " << prev - accurate << std::endl;
    }
    else {
        std::cout << "Accurate is equal to not accurate" << std::endl;
    }

    std::cout << "Not accurate value: " << prev << std::endl;
    std::cout << "Iterations: " << iterations << std::endl;

    return 0;
}