#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:25600000000000000000000000000000000")
#define qq cout << "!!" << endl;
#define ww cout << "??" << endl;
#define rr return 0;
#define nl cout << endl;
#define pb push_back
#define mk make_pair
#define sqr(a) ((a) * (a))
#define imp(a) fixed << setprecision(a)
#define x first
#define y second
#define acmSqrt(a) __asm__ ("fsqrt" : "+t" (a));

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pp;
typedef pair<double, double> point;

int n, z;


struct node {
    int s, a;
};

int *A;
node *tree;

inline void build(int k, int left, int right) {
    if(left == right) {
        tree[k].s = A[left];
        tree[k].a = INT_MAX;
        return;
    }

    register int center = (left + right) / 2;

    build(k * 2, left, center);
    build(k * 2 + 1, center + 1, right);

    tree[k].s = tree[k * 2].s + tree[k * 2 + 1].s;
    tree[k].a = INT_MAX;
}

inline void push(int k, int left, int center, int right) {
    if(tree[k].a != INT_MAX) {
        tree[k * 2].a = tree[k].a;
        tree[k * 2 + 1].a = tree[k].a;

        tree[k * 2].s = (center - left + 1) * tree[k].a;
        tree[k * 2 + 1].s = (right - center) * tree[k].a;

        tree[k].a = INT_MAX;
    }
}

inline void update(int k, int left, int right, int l, int r, int &a) {
    if(l > r) {
        return;
    }

    if(left == l && r == right) {
        tree[k].a = a;
        tree[k].s = (r - l + 1) * a;
        return;
    }

    register int center = (left + right) / 2;

    push(k, left, center, right);

    update(k * 2, left, center, l, min(r, center), a);
    update(k * 2 + 1, center + 1, right, max(l, center + 1), r, a);

    tree[k].s = tree[k * 2].s + tree[k * 2 + 1].s;
}

ll query(int k, int left, int right, int l, int r) {
    if(l > r) {
        rr;
    }

    if(left == l && right == r) {
        return tree[k].s;
    }

    register int center = (left + right) / 2;

    push(k, left, center, right);

    return query(k * 2, left, center, l, min(r, center)) +
           query(k * 2 + 1, center + 1, right, max(l, center + 1), r);
}

int main() {
    ios_base::sync_with_stdio(0);
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    cin >> n >> z;

    A = new int[n];
    tree = new node[4 * n];

    for(register int i = 0; i < n; ++i) {
        cin >> A[i];
    }

    build(1, 0, n - 1);

    while(z--) {
        register string s;
        register int l, r;

        cin >> s >> l >> r;

        if(s == "?") {
            cout << query(1, 0, n - 1, --l, --r) << endl;
        }
        else {
            register int a;
            cin >> a;
            update(1, 0, n - 1, --l, --r, a);
        }
    }
}