#include<bits/stdc++.h>
using namespace std;int main(){cout<<5.5;}

AC了！

#include<bits/stdc++.h>
using namespace std;
int main()
{
    double a,b,c;
    cin >> a >> b >> c;
    c = c - (b *0.9) - (a * 0.9);
    cout << c;
    return 0;
}

简单A

#include <iostream>

#include <iomanip> using namespace std; int main(){ double x,y,n,z; cin >> x >> y >> n; z = x + y; cout << fixed << setprecision(1) << n - z *0.9; return 0; }

#include <bits/stdc++.h> 
using namespace std;
int main(){
    cout<<5.5;
}

5行

过辣!(脑残人士的欢呼)

    long long x,y,n;
    cin>>x>>y>>n;
    cout<<n-0.9*(x+y);

#include <iostream>//hetao3097453
#include <iomanip>
using namespace std;
int main()
{
    double x,y,n,z;
    cin >> x >> y >> n;
    z = x + y;
    cout << fixed << setprecision(1) << n - z * 0.9;
    return 0;
}

号没了

#include <bits/stdc++.h>
using namespace std;
int main()
{
    double x,y,n;
    cin >> x >> y >> n;
    cout << n-(x+y)*0.9;
}