fn net_salary(salary: f64) -> f64 {
    if salary < 200_000.0 {
        salary - 0.13 * salary    
    } else if salary < 416_700.0 {
        let step1_part = 200_000.0 - 200_000.0 * 0.13;
        let step2_part = (salary - 200_000.0) - (salary - 200_000.0) * 0.15;
        step1_part + step2_part
    } else if salary < 1_670_000.0 {
        let step1_part = 200_000.0 - 200_000.0 * 0.13;
        let step2_part = (416_700.0 - 200_000.0) - (416_700.0 - 200_000.0) * 0.15;
        let step3_part = (salary - 416_700.0)  - (salary - 416_700.0) * 0.18;
        step1_part + step2_part + step3_part
    } else if salary < 4_170_000.0 {
        let step1_part = 200_000.0 - 200_000.0 * 0.13;
        let step2_part = (416_700.0 - 200_000.0) - (416_700.0 - 200_000.0) * 0.15;
        let step3_part = (1_670_000.0 - 416_700.0) - (1_670_000.0 - 416_700.0) * 0.18;
        let step4_part = (salary - 1_670_000.0) - (salary - 1_670_000.0) * 0.20;
        step1_part + step2_part + step3_part + step4_part
    } else {
        let step1_part = 200_000.0 - 200_000.0 * 0.13;
        let step2_part = (416_700.0 - 200_000.0) - (416_700.0 - 200_000.0) * 0.15;
        let step3_part = (1_670_000.0 - 416_700.0) - (1_670_000.0 - 416_700.0) * 0.18;
        let step4_part = (4_170_000.0 - 1_670_000.0) - (4_170_000.0 - 1_670_000.0) * 0.20;
        let step5_part = (salary - 4_170_000.0) - (salary - 4_170_000.0) * 0.22;
        step1_part + step2_part + step3_part + step4_part + step5_part
    }
}

fn gross_salary(net_salary: f64) -> f64 {
    if net_salary <= 200_000.0 * (1.0 - 0.13) {
        net_salary / (1.0 - 0.13)
    } else if net_salary <= (200_000.0 * (1.0 - 0.13)) + (216_700.0 * (1.0 - 0.15)) {
        let step1_net = 200_000.0 * (1.0 - 0.13);
        let step2_net = net_salary - step1_net;
        200_000.0 + step2_net / (1.0 - 0.15)
    } else if net_salary <= (200_000.0 * (1.0 - 0.13)) + (216_700.0 * (1.0 - 0.15)) + (1_253_300.0 * (1.0 - 0.18)) {
        let step1_net = 200_000.0 * (1.0 - 0.13);
        let step2_net = (416_700.0 - 200_000.0) * (1.0 - 0.15);
        let step3_net = net_salary - step1_net - step2_net;
        416_700.0 + step3_net / (1.0 - 0.18)
    } else if net_salary <= (200_000.0 * (1.0 - 0.13)) + (216_700.0 * (1.0 - 0.15)) + (1_253_300.0 * (1.0 - 0.18)) + (2_500_000.0 * (1.0 - 0.20)) {
        let step1_net = 200_000.0 * (1.0 - 0.13);
        let step2_net = (416_700.0 - 200_000.0) * (1.0 - 0.15);
        let step3_net = (1_670_000.0 - 416_700.0) * (1.0 - 0.18);
        let step4_net = net_salary - step1_net - step2_net - step3_net;
        1_670_000.0 + step4_net / (1.0 - 0.20)
    } else {
        let step1_net = 200_000.0 * (1.0 - 0.13);
        let step2_net = (416_700.0 - 200_000.0) * (1.0 - 0.15);
        let step3_net = (1_670_000.0 - 416_700.0) * (1.0 - 0.18);
        let step4_net = (4_170_000.0 - 1_670_000.0) * (1.0 - 0.20);
        let step5_net = net_salary - step1_net - step2_net - step3_net - step4_net;
        4_170_000.0 + step5_net / (1.0 - 0.22)
    }
}