#include using namespace std; #define rep(i, n) for(int i = 0; i < n; i++) #define rep2(i, x, n) for(int i = x; i <= n; i++) #define rep3(i, x, n) for(int i = x; i >= n; i--) #define elif else if #define sp(x) fixed << setprecision(x) #define pb push_back #define eb emplace_back #define all(x) x.begin(), x.end() #define sz(x) (int)x.size() using ll = long long; using ld = long double; using pii = pair; using pil = pair; using pli = pair; using pll = pair; const ll MOD = 1e9+7; //const ll MOD = 998244353; const int inf = (1<<30)-1; const ll INF = (1LL<<60)-1; const ld EPS = 1e-10; template bool chmax(T &x, const T &y) {return (x < y)? (x = y, true) : false;}; template bool chmin(T &x, const T &y) {return (x > y)? (x = y, true) : false;}; int main(){ ll A[5]; rep(i, 5) cin >> A[i]; ll l = 0, r = 1LL<<50; //[l, r) while(r-l > 1){ ll m = (l+r)/2; ll num[5]; rep(i, 5){ if(A[i]-m > 0) num[i] = 0; else num[i] = m-A[i]; } ll M = 0; rep(i, 5) M += num[i]; M = (M+1)/2; rep(i, 5){ int j = (i+2)%5; chmax(M, num[i]+num[j]); } if(M <= m) l = m; else r = m; } cout << l << endl; }