#include <iostream>
#include <iomanip>
using namespace std;
int main() {
double n;
cin>>n;
if (n <= 50) {
cout<<fixed<<setprecision(3)<<25000+ (n*600)<<endl;
} else if (n<=150) {
cout<<fixed<<setprecision(3)<<25000+50*600+(n-50)*400<<endl;
} else {
cout<<fixed<<setprecision(3)<<25000+50*600+150*400+(n-50-150)*200<<endl;
}
return 0;
}

$#doanthevu$

Code C++ :

#include <bits/stdc++.h>
using namespace std;
#define phithue 25000
#define cuocgoidautien 600
#define cuocgoithuhai 400
#define cuocgoithuba 200
int tonghet(int n) {
    int tongcong = phithue;
    if (n > 50) {
        tongcong += 50 * cuocgoidautien;
        n -= 50;
    } else {
        tongcong += n * cuocgoidautien;
        return tongcong;
    }
    if (n > 150) {
        tongcong += 150 * cuocgoithuhai;
        n -= 150;
    } else {
        tongcong += n * cuocgoithuhai;
        return tongcong;
    }
    tongcong += n * cuocgoithuba;
    return tongcong;
}

int main() {
    int n;
    cin >> n;
    int tongcong = tonghet(n);
    cout << tongcong << endl;
    return 0;
}