Language: C++

#include <cassert>
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
/*
//#if __cplusplus >= 201103L
#include <ccomplex>
#include <cfenv>
#include <cinttypes>
#include <cstdbool>
#include <cstdint>
#include <ctgmath>
#include <cwchar>
#include <cwctype>
*/

// C++
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
/*
//#if __cplusplus >= 201103L
#include <array>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
*/
using namespace std;
#define fi first
#define se second
#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define each(itr,v) for(auto itr:v)
#define pb(s) push_back(s)
#define mmax(x,y) (x>y?x:y)
#define mmin(x,y) (x<y?x:y)
#define maxch(x,y) x=mmax(x,y)
#define minch(x,y) x=mmin(x,y)
#define mp(a,b) make_pair(a,b)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl

#define uni(x) x.erase(unique(all(x)),x.end())
template<class T,class U>inline void chmin(T &t,U f){if(t>f)t=f;}
template<class T,class U>inline void chmax(T &t,U f){if(t<f)t=f;}
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) > (b) ? (b) : (a))

typedef long long ll;
typedef unsigned long long ull;
typedef pair<double,double> P;
typedef pair<P, int> PPI;

#define INF INT_MAX/3
#define MAX_N 1000
#define M_INF 1000000000
int n,m,v,i;
void solve(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  std::vector<P> v(4);
  
  cin>>v[0].fi>>v[1].fi>>v[2].fi>>v[3].fi;
  v[1].fi /= 2.0;
  v[2].fi /= 4.0;
  v[3].fi /= 8.0;
  cin>>n;
  rep(i,4) v[i].se = 0.25*pow(2,i);
  // cout<<0.25*pow(2,1)<<endl;
  // rep(i,4) cout<<v[i].se<<endl;
  sort(all(v));
  ll ans = 0;
  // rep(i,4) cout<<v[i].se<<endl;
  int flg = 0;
  while(n != 0 && flg < 4){
    double l = n/v[flg].se;
    unsigned ll o = (unsigned ll)l;
    ans += v[flg].fi * (v[flg].se/0.25) *o;
    n -= v[flg].se * o;
    flg++;
  }
  cout<<ans<<endl;
}

int main(){
  solve();
  return 0;
}


Compiler output:
a.cc: In function 'void solve()':
a.cc:132:17: error: expected initializer before 'o'
  132 |     unsigned ll o = (unsigned ll)l;
      |                 ^
a.cc:133:42: error: 'o' was not declared in this scope
  133 |     ans += v[flg].fi * (v[flg].se/0.25) *o;
      |                                          ^