#include <cstdint>
#include <iostream>
#include <cstdlib>

using namespace std;

inline int64_t sign(int64_t x) {
    return (x > 0) - (x < 0);
}

int main() {
#ifdef ONLINE_JUDGE
    freopen("operations.in", "r", stdin);
    freopen("operations.out", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    int64_t n;

    cin>>n;

    int64_t prvsgn = 0;
    int64_t sum = 0;
    int64_t best = 0;

    while (n--) {
        int64_t a, sgn;
        cin>>a;
        if (!a) continue;
        sgn = sign(a);

        if (sgn != prvsgn) {
            if (sum < 0) sum = -sum;
            if (sum > best) best = sum;

            // cout<<sum<<endl;
            prvsgn = sgn;
            sum = 0;
        }

        sum += a;
    }

    if (sum < 0) sum = -sum;
    // cout<<sum<<endl;
    if (sum > best) best = sum;

    cout<<best<<'\n';
}