#include <bits/stdc++.h>

#define fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)
#define fth(t) std::get<3>(t)
#define unless(p) if(!(p))
#define until(p) while(!(p))

using ll = long long;
using P = std::tuple<int,int>;

const int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};

constexpr ll INF = 1001001001001001001;
int N, Q;

struct SegmentTree{
    struct Node{
        ll sum, leftSum, rightSum, max;
    };
    
    int numLeaf;
    std::vector<Node> data;

    SegmentTree(int n){
        numLeaf = 1;
        while(numLeaf < n){
            numLeaf *= 2;
        }

        data.assign(numLeaf * 2, {0, 0, 0, -INF});
    }

    Node merge(Node n1, Node n2){
        ll s = n1.sum + n2.sum,
           ls = std::max(n1.leftSum, n1.sum + n2.leftSum),
           rs = std::max(n2.rightSum, n2.sum + n1.rightSum),
           mx = std::max({n1.rightSum + n2.leftSum, n1.max, n2.max});
        
        return {s, ls, rs, mx};
    }

    void set(int k, ll v){
        k += numLeaf;

        data[k] = {v, v, v, v};

        while(k > 1){
            k /= 2;

            data[k] = merge(data[k*2], data[k*2+1]);
        }
    }

    Node query(int l, int r){
        if(l >= r){
            return {0, -INF, -INF, -INF};
        }

        std::queue<int> idx_l;
        std::stack<int> idx_r;

        l += numLeaf;
        r += numLeaf;
        for(;l<r;l/=2,r/=2){
            if(l & 1){
                idx_l.emplace(l);
                l += 1;
            }
            if(r & 1){
                r -= 1;
                idx_r.emplace(r);
            }
        }

        until(idx_r.empty()){
            idx_l.emplace(idx_r.top());
            idx_r.pop();
        }

        Node res = data[idx_l.front()];
        idx_l.pop();
        
        until(idx_l.empty()){
            res = merge(res, data[idx_l.front()]);
            idx_l.pop();
        }

        return res;
    }
};

int main(){
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    std::cin >> N >> Q;

    SegmentTree seg(N);
    for(int i=0;i<N;++i){
        int A;
        std::cin >> A;

        seg.set(i, A);
    }

    for(int i=0;i<Q;++i){
        std::string type;
        std::cin >> type;

        if(type[0] == 's'){
            int i;
            ll x;
            std::cin >> i >> x;

            --i;

            seg.set(i, x);
        }else{
            int l1, l2, r1, r2;
            std::cin >> l1 >> l2 >> r1 >> r2;

            --l1; --l2; --r1; --r2;
            r1 = std::max(r1, l1);
            l2 = std::min(l2, r2);

            ll res;
            if(l2 < r1){
                SegmentTree::Node
                    n1 = seg.query(l1, l2 + 1),
                    n2 = seg.query(l2 + 1, r1),
                    n3 = seg.query(r1, r2 + 1);
                
                res = n1.rightSum + n2.sum + n3.leftSum;
            }else{
                SegmentTree::Node
                    n1 = seg.query(l1, r1),
                    n2 = seg.query(r1, l2 + 1),
                    n3 = seg.query(l2 + 1, r2 + 1);

                res = std::max({n2.max,
                                n1.rightSum + n2.leftSum,
                                n2.rightSum + n3.leftSum,
                                n1.rightSum + n2.sum + n3.leftSum});
            }
            
            std::cout << res << std::endl;
        }
    }
}