Go: package main

import (
	"bufio"
	"os"
	"strconv"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

func nextInt() int {
	scanner.Scan()
	i, e := strconv.Atoi(scanner.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func max(x, y int) int {
	if x > y {
		return x
	} else {
		return y
	}
}

func main() {
	sum := make([]int, 5001)
	for {
		n := nextInt()
		if n == 0 {
			break
		}
		for i := 0; i < n; i++ {
			a := nextInt()
			sum[i+1] = sum[i]+a
		}
		ret := sum[1]
		for i := 0; i <= n; i++ {
			for j := i + 1; j <= n; j++ {
				ret = max(ret, sum[j]-sum[i])
			}
		}
		fmt.Println(ret)
	}
}

C++: // need
#include <iostream>
#include <algorithm>

// data structure
#include <bitset>
//#include <list>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>
//#include <array>
//#include <tuple>
//#include <unordered_map>
//#include <unordered_set>
#include <complex>
//#include <deque>
#include<valarray>

// stream
//#include <istream>
//#include <sstream>
//#include <ostream>
#include <fstream>

// etc
#include <cassert>
#include <functional>
#include <iomanip>
//#include <typeinfo>
//#include <chrono>
#include <random>
#include <numeric>

#define INIT std::ios::sync_with_stdio(false);std::cin.tie(0);
#define VAR(type, ...)type __VA_ARGS__;MACRO_VAR_Scan(__VA_ARGS__);
template<typename T> void MACRO_VAR_Scan(T& t) { std::cin >> t; }
template<typename First, typename...Rest>void MACRO_VAR_Scan(First& first, Rest&...rest) { std::cin >> first; MACRO_VAR_Scan(rest...); }
#define VEC_ROW(type, n, ...)std::vector<type> __VA_ARGS__;MACRO_VEC_ROW_Init(n, __VA_ARGS__); for(int i=0; i<n; ++i){MACRO_VEC_ROW_Scan(i, __VA_ARGS__);}
template<typename T> void MACRO_VEC_ROW_Init(int n, T& t) { t.resize(n); }
template<typename First, typename...Rest>void MACRO_VEC_ROW_Init(int n, First& first, Rest&...rest) { first.resize(n); MACRO_VEC_ROW_Init(n, rest...); }
template<typename T> void MACRO_VEC_ROW_Scan(int p, T& t) { std::cin >> t[p]; }
template<typename First, typename...Rest>void MACRO_VEC_ROW_Scan(int p, First& first, Rest&...rest) { std::cin >> first[p]; MACRO_VEC_ROW_Scan(p, rest...); }
#define OUT(d) std::cout<<d;
#define FOUT(n, d) std::cout<<std::fixed<<std::setprecision(n)<<d;
#define SOUT(n, c, d) std::cout<<std::setw(n)<<std::setfill(c)<<d;
#define SP std::cout<<" ";
#define TAB std::cout<<"\t";
#define BR std::cout<<"\n";
#define SPBR(i, n) std::cout<<(i + 1 == n ? '\n' : ' ');
#define ENDL std::cout<<std::endl;
#define FLUSH std::cout<<std::flush;
#define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)std::cin>>i;
#define MAT(type, c, m, n) std::vector<std::vector<type>> c(m, std::vector<type>(n));for(auto& r:c)for(auto& i:r)std::cin>>i;
#define ALL(a) (a).begin(),(a).end()
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define RFOR(i, a, b) for(int i=(b)-1;i>=(a);--i)
#define REP(i, n) for(int i=0;i<int(n);++i)
#define RREP(i, n) for(int i=(n)-1;i>=0;--i)
#define FORLL(i, a, b) for(ll i=ll(a);i<ll(b);++i)
#define RFORLL(i, a, b) for(ll i=ll(b)-1;i>=ll(a);--i)
#define REPLL(i, n) for(ll i=0;i<ll(n);++i)
#define RREPLL(i, n) for(ll i=ll(n)-1;i>=0;--i)
#define PAIR std::pair<int, int>
#define PAIRLL std::pair<ll, ll>
#define IN(a, x, b) (a<=x && x<b)
#define SHOW(d) {std::cerr << #d << "\t:" << d << "\n";}
#define SHOWVECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOWVECTOR2(v) {std::cerr << #v << "\t:\n";for(const auto& xxx : v){for(const auto& yyy : xxx){std::cerr << yyy << " ";}std::cerr << "\n";}}
#define SHOWPAIR(p) {std::cerr << #p << "\t:(" << p.first << ",\t" << p.second << ")\n";}
#define SHOWPAIRVECTOR2(v) {std::cerr << #v << "\t:\n";for(const auto& xxx : v){for(const auto& yyy : xxx){std::cerr<<'('<<yyy.first<<", "<<yyy.second<<") ";}std::cerr << "\n";}}
#define SHOWPAIRVECTOR(v) {for(const auto& xxx:v){std::cerr<<'('<<xxx.first<<", "<<xxx.second<<") ";}std::cerr<<"\n";}
#define SHOWQUEUE(a) {auto tmp(a);std::cerr << #a << "\t:";while(!tmp.empty()){std::cerr << tmp.front() << " ";tmp.pop();}std::cerr << "\n";}
template<typename T> inline T CHMAX(T& a, const T b) { return a = (a < b) ? b : a; }
template<typename T> inline T CHMIN(T& a, const T b) { return a = (a > b) ? b : a; }
#define EXCEPTION(msg) throw std::string("Exception : " msg " [ in ") + __func__ + " : " + std::to_string(__LINE__) + " lines ]"
#define TRY(cond, msg) try {if (cond) EXCEPTION(msg);}catch (std::string s) {std::cerr << s << std::endl;}
//void CHECKTIME(std::function<void()> f) { auto start = std::chrono::system_clock::now(); f(); auto end = std::chrono::system_clock::now(); auto res = std::chrono::duration_cast<std::chrono::nanoseconds>((end - start)).count(); std::cerr << "[Time:" << res << "ns  (" << res / (1.0e9) << "s)]\n"; }

#define int ll
using ll = long long;
using ull = unsigned long long;
constexpr int INFINT = 1 << 30;                          // 1.07x10^ 9
constexpr int INFINT_LIM = (1LL << 31) - 1;              // 2.15x10^ 9
constexpr ll INFLL = 1LL << 60;                          // 1.15x10^18
constexpr ll INFLL_LIM = (1LL << 62) - 1 + (1LL << 62);  // 9.22x10^18
constexpr double EPS = 1e-7;
constexpr int MOD = 1000000007;
constexpr double PI = 3.141592653589793238462643383279;

signed main() {
	INIT;
	int n;
	while (std::cin >> n) {
		if (n == 0) break;
		VEC(int, a, n);
		std::vector<int> c(n+1, 0);
		int ans = -INFINT;
		REP(i, n) {
			c[i + 1] = c[i] + a[i];
		}
		std::map<int, int> map;
		RREP(i, c.size()) {
			if (!map.empty()) {
				auto it = map.rbegin();
				CHMAX(ans, it->first - c[i]);
			}
			map[c[i]];
		}
		OUT(ans)BR;
	}
	return 0;
}

C++: #include <iostream>

using namespace std;

/** Problem0022 : Maximum Sum Sequence **/

int main()
{
	int n, num[5001]={0}, s;
	int maxNum;
	
	while (1) {
		cin >> n;
		if (n==0) break;
		for (int i=0; i<n; i++) {
			cin >> num[i];
		}
		
		maxNum = num[0];
		for (int i=0; i<n; i++) {
			s=0;
			for (int j=i; j<n; j++) {
				s+=num[j];
				if (s>maxNum)
					maxNum=s;
			}
		}
		cout << maxNum << endl;
	}
}

C++: #include<iostream>
#include<vector>

using namespace std;

int getMaxSum(vector<int> v)
{
	int sum,max;
	sum=v[0];
	max=v[0];
	for(int i=1;i<v.size();i++)
	{
		if(sum<0)
		{
			sum=0;
		}
		sum+=v[i];
		if(sum>max)
		{
			max=sum;
		}
	}
	return max;
}

int main(void)
{
	int n;
	while(cin>>n)
	{
		if(n==0)
		{
			break;
		}
		vector<int> v;
		for(int i=0;i<n;i++)
		{
			int tmp;
			cin>>tmp;
			v.push_back(tmp);
		}
		cout<<getMaxSum(v)<<endl;
	}
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
int main()
{
	while (1) {
		int a[5001] = { 0 };
		int n;
		cin >> n;
		if (n == 0)break;
		a[0] = 0;
		int maxv = -100000;
		for (int i = 1; i <= n; i++) {
			cin >> a[i];
		}
		for (int i = 1; i <= n; i++) {
			a[i] = max(a[i], a[i] + a[i - 1]);
			maxv = max(maxv, a[i]);
		}
		cout << maxv << endl;
	}
}

C++: #include<iostream>
using namespace std;
bool same(int a,int b){
  if(a*b>=0) return true;
  return false;
}
int main(){
  int n;
  while(cin>>n){
    if(n==0) break;
    int d;
    int s[n];
    int count = 0,begin = 0;
    int ans;
    for(int i=0;i<n;i++){
      cin >> d;
      if(i==0) s[0] = d;
      else if(same(d,s[count])) s[count] += d;
      else{
	count++;
	s[count] = d;
      }     
    }
    if(count==0){
      cout << s[0] << endl;
      continue;
    } 
    if(s[0]<0) begin = 1;
    for(int i=begin;i<=count;i+=2){
      unsigned long long int h = s[i];
      if(i==begin) ans = s[i];
      else if(ans<h) ans = h;
      for(int j=i+1;j<=count;j++){
	h += s[j];
	if(ans<h) ans = h;
      }
    }
    cout << ans << endl;
  }
  return 0;
}