#include <iostream>
#include <iomanip>
#include <cassert>
#include <vector>
#include <algorithm>
#include <utility>
#include <numeric>
#include <tuple>
#include <ranges>
namespace ranges = std::ranges;
namespace views = std::views;
// #include "Src/Number/IntegerDivision.hpp"
// #include "Src/Utility/BinarySearch.hpp"
// #include "Src/Sequence/CompressedSequence.hpp"
// #include "Src/Sequence/RunLengthEncoding.hpp"
// #include "Src/Algebra/Group/AdditiveGroup.hpp"
// #include "Src/DataStructure/FenwickTree/FenwickTree.hpp"
// #include "Src/DataStructure/SegmentTree/SegmentTree.hpp"
// #include "Src/DataStructure/DisjointSetUnion/DisjointSetUnion.hpp"
// using namespace zawa;
// #include "atcoder/modint"
// using mint = atcoder::modint998244353;
using namespace std;
int N;
string S;
int main() {
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);
    cin >> N >> S;
    vector<int> dp(2, -1);
    dp[0] = 0;
    for (char c : S) {
        vector<int> next = dp;
        if (c == '-') next[0] = dp[0] + 1;
        else if (c == '0') next[1] = max(dp[1], dp[0] + 1);
        else if (c == '+') next[1] = max(dp[0], dp[1]) + 1;
        dp = move(next);
    }
    cout << *ranges::max_element(dp) << '\n';
}