Go: package main

import "fmt"

func main() {
	var result []int
	for {
		var n, a, maxSum int
		fmt.Scan(&n)

		if n == 0 {
			break
		}

		maxSum = 0
		sum := 0
		for i := 0; i < n; i++ {
			fmt.Scan(&a)
			if i == 0 {
				sum = a
				maxSum = sum
			} else if sum+a < a {
				sum = a
				if maxSum < sum {
					maxSum = sum
				}
			} else {
				sum = sum + a
				if maxSum < sum {
					maxSum = sum
				}
			}
		}

		result = append(result, maxSum)
	}

	for _, v := range result {
		fmt.Println(v)
	}
}

C++: #define _USE_MATH_DEFINES
#include<iostream>
#include<string>
#include<queue>
#include<cmath>
#include<map>
#include<set>
#include<list>
#include<iomanip>
#include<vector>
#include<random>
#include<functional>
#include<algorithm>
#include<stack>
#include<cstdio>
#include<bitset>
#include<unordered_map>
#include<climits>
#include<fstream>
using namespace std;
///////////////////library zone!!!!!!!!!!!!!!!!!!!!!!!!!!!!
typedef long long ll;
typedef long double ld;
#define all(a) (a).begin(),(a).end()
#define EPS (1e-7)
const ll Mod = 1000000007;
const ll mod = 998244353;
struct H {
	ll x, y;
	bool operator<(const H &b) const {
		if (x != b.x) return x < b.x;
		return y < b.y;
	}
	bool operator>(const H &b) const {
		if (x != b.x) return x > b.x;
		return y > b.y;
	}
	bool operator==(const H &b) const { return x == b.x&&y == b.y; }
	bool operator!=(const H &b) const { return (*this) != b; }
};
struct P {
	ll pos, cost;
	bool operator<(const P &b) const { return cost < b.cost; }
	bool operator>(const P &b) const { return cost > b.cost; }
};
struct B {
	ll to, cost;
};
struct E {
	ll from, to, cost;
	bool operator<(const E &b) const { return cost < b.cost; }
	bool operator>(const E &b) const { return cost > b.cost; }
};
template<typename T, typename U>
void chmin(T &a, U b) {
	if (a > b) a = b;
}
template<typename T, typename U>
void chmax(T &a, U b) {
	if (a < b) a = b;
}
template<typename T>
T max_0(T a) {
	if (a < 0) return 0;
	return a;
}
template<typename T>
T min_0(T a) {
	if (a > 0) return 0;
	return a;
}
ll read() {
	ll u;
	ll k = scanf("%lld", &u);
	return u;
}
ll gcd(ll i, ll j) {
	if (i > j) swap(i, j);
	if (i == 0) return j;
	return gcd(j%i, i);
}
ll mod_pow(ll x, ll n, ll p) {
	ll res = 1;
	while (n > 0) {
		if (n & 1) res = res * x % p;
		x = x * x % p;
		n >>= 1;
	}
	return res;
}//x^n%p
vector<string>split(string s, char c = ' ') {
	vector<string>vec;
	string h = "";
	for (int i = 0; i < s.size();) {
		int j = i;
		while (j < s.size() && s[j] != ' ') {
			h += s[j++];
		}
		if (h.size() > 0) vec.push_back(h);
		h = "";
		i = j + 1;
	}
	return vec;
}
const ll Inf = 3023372036854775807;
const int inf = 1500000000;
#define int long long
//----------------------------------------------------
class Vec2 {
public:
	ld x, y;
	Vec2() { x = 0, y = 0; }
	Vec2(ld x, ld y) :x(x), y(y) {}
	ld length() {
		return sqrt(x*x + y * y);
	}
	Vec2 normal() {
		ld len = this->length();
		if (len == 0) return Vec2(x, y);
		x /= len, y /= len;
		return *(this);
	}
	Vec2 operator+(Vec2 vec) {
		return Vec2(x + vec.x, y + vec.y);
	}
	Vec2 operator-(Vec2 vec) {
		return Vec2(x - vec.x, y - vec.y);
	}
	template<typename T>
	Vec2 operator*(T cons) {
		return Vec2(x*cons, y*cons);
	}
	ld operator*(Vec2 vec) {
		return x * vec.x + y * vec.y;
	}
	ld operator%(Vec2 vec) {
		return x * vec.y - y * vec.x;
	}
	bool operator==(Vec2 vec) {
		return abs(x - vec.x) < EPS && abs(y - vec.y) < EPS;
	}
};
ld dot(Vec2 a, Vec2 b) {
	return a.x*b.x + a.y*b.y;
}
ld cross(Vec2 a, Vec2 b) {
	return a.x*b.y - a.y*b.x;
}
ld areaIntegral(Vec2 a, Vec2 b) {
	return abs(a.x*b.y - a.y*b.x) / 2.0;
}
class Vec3 {
public:
	ld x, y, z;
	Vec3() { x = 0, y = 0, z = 0; }
	Vec3(ld x, ld y, ld z) :x(x), y(y), z(z) {}
	ld length() {
		return sqrt(x*x + y * y + z * z);
	}
	void normal() {
		ld len = this->length();
		if (len == 0) return;
		x /= len, y /= len, z /= len;
	}
	Vec3 operator+(Vec3 vec) {
		return Vec3(x + vec.x, y + vec.y, z + vec.z);
	}
	Vec3 operator-(Vec3 vec) {
		return Vec3(x - vec.x, y - vec.y, z - vec.z);
	}
	Vec3 operator*(int cons) {
		return Vec3(x*cons, y*cons, z*cons);
	}
	ld operator*(Vec3 vec) {
		return x * vec.x + y * vec.y + z * vec.z;
	}
};
ld dot(Vec3 a, Vec3 b) {
	return a.x*b.x + a.y*b.y + a.z*b.z;
}
class Line {
public:
	Vec2 from, to;
	Line(Vec2 from, Vec2 to) :from(from), to(to) {}
};
Line getPerpendicularBisector(Line line) {
	int cx = (line.from.x + line.to.x) / 2, cy = (line.from.y + line.to.y) / 2;
	Vec2 p = Vec2(cx + (line.from.y - line.to.y), cy + (line.to.x - line.from.x));
	return Line(Vec2(cx, cy), p);
}
signed main() {
	int n;
	while (cin >> n && n) {
		int a[10000];
		for (int i = 0; i < n; i++) cin >> a[i];
		int ans = -Inf;
		for (int i = 1; i <= n; i++) {
			int sum = 0;
			for (int j = 0; j < i; j++) sum += a[j];
			ans = max(ans, sum);
			for (int j = 0; j < n - i; j++) {
				sum -= a[j];
				sum += a[j + i];
				ans = max(ans, sum);
			}
		}
		cout << ans << endl;
	}
}

C++: #include<iostream>
#include<string>
#include<cstdio>
#include<algorithm>
#include<stack>
#include<queue>
#include<vector>
#include<cmath>
#include<utility>
#include<set>
#include<complex>
#include<map>
#define vi vector<int>
#define vvi vector<vector<int> >
#define ll long long int
#define vl vector<ll>
#define vvl vector<vector<ll>>
#define vb vector<bool>
#define vc vector<char>
#define vs vector<string>
#define ld long double
#define INF 1e9
#define EPS 0.0000000001
#define rep(i,n) for(int i=0;i<n;i++)
#define loop(i,s,n) for(int i=s;i<n;i++)
#define CC puts("-------ok--------");
#define all(in) in.begin(), in.end()
using namespace std;
typedef pair<int, int> pii;
#define MAX 99999999
int main(){
    int n;
    while(cin>>n,n){
        vi v(n+1,0);
        rep(i,n)cin>>v[i];
        ll ans=0, temp;
        
        for(int i=0;i<n;i++){
            temp=0;
            for(int j=i;j<n;j++){
                temp+=v[j];
                ans=max(ans,temp);
            }
        }
        cout<<ans<<endl;
    }
}

C++: #include <stdio.h>
#include <algorithm>
#include <functional>
using namespace std;

int main(){
	int n,i,num[5000];
	long long int sum[5001];
	while(1){
		sum[0] = 0;
		scanf("%d",&n);
		if(!n) break;
		for(i = 0;i < n;i++){
			scanf("%d",&num[i]);
			sum[i + 1] = sum[i] + num[i];
		}
		sort(sum,sum + n + 1,greater<long long>());
		printf("%lld\n",sum[0] - sum[n]);
	}
	return 0;
}

C++: #include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
#define rep(i,a,n) for(int i=a;i<n;i++)
#define REP(i,n) rep(i,0,n);
const int MIN_INT = -9999999;

int main(int argc, char *argv[]) {
	int dataN;
	while (EOF != fscanf(stdin, "%d", &dataN)) {
		if (dataN == 0) break;
		const int c_N = dataN;
		int tmp, sums[c_N], max_v=MIN_INT;
		memset(sums, 0, sizeof(sums));
		for (int i = 0; i < c_N; i++) {
			fscanf(stdin, "%d", &tmp);
			sums[i] += tmp;
			max_v = max(max_v, sums[i]);
			for (int j = 0; j < i; j++) {
				sums[j] += tmp;
				max_v = max(max_v, sums[j]);
			}
		}
		printf("%d\n", max_v);
	}
	return 0;
}

C++: #include <iostream>

using namespace std;

int main() {
    int n = 0;
    while (cin>>n && n != 0) {
        int a[5001] = {};
        int max = -1000000;
        for (int i = 0; i < n; i++) {
            cin>>a[i];
            if (a[i] >= 0) {
                int temp = 0;
                for (int s = i; s >= 0; s--) {
                    temp += a[s];
                    if (temp > max) max = temp;
                    if (temp < 0) break;
                }
            }
        }
        cout<<max<<endl;
    }
}