#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <queue>
#include <random>
#include <regex>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <sys/timeb.h>
#include <vector>

using namespace std;

#define repr(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
#define rep(i, n) repr(i, 0, n)
#define reprrev(i, a, b) for (int i = (int)(b)-1; i >= (int)(a); i--)
#define reprev(i, n) reprrev(i, 0, n)
#define repi(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++)
#define chmin(mi, val) mi = min(mi, val)
#define chmax(ma, val) ma = max(ma, val)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define mp make_pair
#define mt make_tuple
#define INF 1050000000
#define INFR INT_MAX
#define INFL (long long)(4e18)
#define INFLR LLONG_MAX
#define EPS (1e-10)
#define MOD 1000000007
//#define MOD 998244353
#define PI 3.141592653589793238
#define RMAX 4294967295

typedef long long ll;
typedef pair< int, int > Pi;
typedef pair< ll, ll > Pll;
typedef pair< double, double > Pd;
typedef vector< int > vi;
typedef vector< ll > vll;
typedef vector< bool > vb;
typedef vector< char > vc;
typedef vector< string > vs;
typedef vector< double > vd;
typedef vector< Pi > vPi;
typedef vector< Pll > vPll;
typedef vector< Pd > vPd;
typedef vector< vector< int > > vvi;
typedef vector< vector< bool > > vvb;
typedef vector< vector< ll > > vvll;
typedef vector< vector< char > > vvc;
typedef vector< vector< string > > vvs;
typedef vector< vector< double > > vvd;
typedef vector< vector< Pi > > vvPi;
typedef vector< vector< vector< int > > > vvvi;
typedef vector< vector< vector< ll > > > vvvll;
typedef vector< vector< vector< Pi > > > vvvPi;
typedef vector< vector< vector< vector< Pi > > > > vvvvPi;
typedef priority_queue< int, vector< int >, greater< int > > pqli;
typedef priority_queue< ll, vector< ll >, greater< ll > > pqlll;
typedef priority_queue< Pi, vector< Pi >, greater< Pi > > pqlP;
template < class T >
using vec = vector< T >;
template < class T >
using pql = priority_queue< T, vector< T >, greater< T > >;

// vvvvvvvvvvvvvvvvvvvvvvv debug output vvvvvvvvvvvvvvvvvvvvvvv
// vector
template < typename T >
istream &operator>>(istream &is, vector< T > &vec) {
    for (T &x : vec) is >> x;
    return is;
}
// pair
template < typename T, typename U >
ostream &operator<<(ostream &os, pair< T, U > &pair_var) {
    os << "(" << pair_var.first << "," << pair_var.second << ")";
    return os;
}
// pair
template < typename T, typename U >
ostream &operator<<(ostream &os, const pair< T, U > &pair_var) {
    os << "(" << pair_var.first << "," << pair_var.second << ")";
    return os;
}
// vector
template < typename T >
ostream &operator<<(ostream &os, const vector< T > &vec) {
    os << "{";
    for (int i = 0; i < vec.size(); i++) {
        os << vec[i] << (i + 1 == vec.size() ? "" : ", ");
    }
    os << "}";
    return os;
}
// map
template < typename T, typename U >
ostream &operator<<(ostream &os, map< T, U > &map_var) {
    os << "{";
    repi(itr, map_var) {
        os << "(" << itr->first << "," << itr->second << ")";
        itr++;
        if (itr == map_var.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}
// set
template < typename T >
ostream &operator<<(ostream &os, set< T > &set_var) {
    os << "{";
    repi(itr, set_var) {
        os << "  " << *itr << endl;
        itr++;
        if (itr == set_var.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}

#define DUMPOUT cerr

void dump_func() {
    DUMPOUT << endl;
}
template < class Head, class... Tail >
void dump_func(Head &&head, Tail &&... tail) {
    DUMPOUT << head;
    if (sizeof...(Tail) > 0) {
        DUMPOUT << ", ";
    }
    dump_func(std::move(tail)...);
}
#ifdef DEBUG_
#define DEB
#define dump(...)                                                              \
    DUMPOUT << "  " << string(#__VA_ARGS__) << ": "                            \
            << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]"        \
            << endl                                                            \
            << "    ",                                                         \
        dump_func(__VA_ARGS__)
#else
#define DEB if (false)
#define dump(...)
#endif

// ^^^^^^^^^^^^^^^^^^^^^^^ debug output ^^^^^^^^^^^^^^^^^^^^^^^

string YN(bool y, int id = 0) {
    if (id) cout << id;
    return (y ? "YES" : "NO");
}
string yn(bool y, int id = 0) {
    if (id) cout << id;
    return (y ? "Yes" : "No");
}
string ON(bool y, int id = 0) {
    if (id) cout << id;
    return (y ? "OK" : "NG");
}

int dir4[4][2] = {{0, -1}, {-1, 0}, {1, 0}, {0, 1}};
int dir8[8][2] = {{-1, -1}, {0, -1}, {1, -1}, {-1, 0},
                  {1, 0},   {-1, 1}, {0, 1},  {1, 1}};
char dirchar[4] = {'<', '^', '>', 'v'};

// [a,b)
int irand(int a, int b) {
    static mt19937 Rand(static_cast< unsigned int >(time(nullptr)));
    uniform_int_distribution< int > dist(a, b - 1);
    return dist(Rand);
}

// [a,b)
double drand(int a, int b) {
    static mt19937 Rand(static_cast< unsigned int >(time(nullptr)));
    uniform_real_distribution< double > dist(a, b);
    return dist(Rand);
}

// 多次元vector生成
template < class T >
vector< T > make_v(size_t size, const T &init) {
    return vector< T >(size, init);
}
template < class... Ts >
auto make_v(size_t size, Ts... rest) {
    return vector< decltype(make_v(rest...)) >(size, make_v(rest...));
}

template < typename T >
T max(vector< T > a) {
    return *max_element(all(a));
}
template < typename T >
T min(vector< T > a) {
    return *min_element(all(a));
}
template < typename T >
T sum(vector< T > a) {
    return accumulate(all(a), (T)0);
}

template < typename T >
void add(map< T, int > &m, T item) {
    if (m.find(item) == m.end()) {
        m[item] = 1;
    } else {
        m[item]++;
    }
}

template < typename T, typename U >
U get(map< T, U > m, T key, U def) {
    if (m.find(key) == m.end()) {
        return def;
    } else {
        return m[key];
    }
}

template < typename T >
bool contains(set< T > t, const T &key) {
    return t.find(key) != t.end();
}

struct Edge {
    int from, to, cost;
    bool operator<(Edge e) {
        return cost < e.cost;
    }
};
using Graph = vec< vec< Edge > >;

ostream &operator<<(ostream &os, Edge &edge) {
    os << "(" << edge.from << "->" << edge.to << ":" << edge.cost << ")";
    return os;
}

//======================================================

// 区間加算区間和型
template < class T, class U >
class LazySegTree {
    int n;
    vector< T > dat;
    vector< U > lazy;
    vector< int > width;

    function< T(T, T) > operation;
    function< T(T, U) > adapt_lazy;
    function< U(U, U) > merge_lazy;
    function< U(U, int) > multiply_lazy;

    T init, def, lazy_def;

    // ツリー上のノード k に lazy 値 v をセット
    void set_lazy(int k, U v) {
        if (lazy[k] == lazy_def) {
            lazy[k] = v;
            dat[k] = adapt_lazy(dat[k], multiply_lazy(v, width[k]));
        } else {
            lazy[k] = merge_lazy(lazy[k], v);
            dat[k] = adapt_lazy(dat[k], multiply_lazy(v, width[k]));
        }
    }
    // lazy を 1 段下ろす
    void push(int k) {
        if (lazy[k] == lazy_def) return;
        set_lazy(k * 2 + 1, lazy[k]);
        set_lazy(k * 2 + 2, lazy[k]);
        lazy[k] = lazy_def;
    }

    // 区間[a,b)の区間クエリ。ノードk=[l,r)に着目している。
    long long _query(int a, int b, int k, int l, int r) {
        if (r <= a || b <= l) return def; // 交差しない
        if (a <= l && r <= b) return dat[k]; // a,l,r,bの順で完全に含まれる
        push(k);
        long long c1 = _query(a, b, 2 * k + 1, l, (l + r) / 2); // 左の子
        long long c2 = _query(a, b, 2 * k + 2, (l + r) / 2, r); // 右の子
        return operation(c1, c2);
    }

  public:
    // _n:必要サイズ, _def:初期値, _operation:クエリ関数,
    // _adapt_lazy:区間作用素適用関数, _merge_lazy:区間作用素マージ関数,
    // _multiply_lazy:作用素を要素数で変形
    LazySegTree(size_t _n, T _init, T _def, T _lazy_def,
                function< T(T, T) > _operation, function< T(T, U) > _adapt_lazy,
                function< U(U, U) > _merge_lazy,
                function< U(U, int) > _multiply_lazy = [](U u,
                                                          int n) { return u; })
        : init(_init), def(_def), lazy_def(_lazy_def), operation(_operation),
          adapt_lazy(_adapt_lazy), merge_lazy(_merge_lazy),
          multiply_lazy(_multiply_lazy) {
        n = 1;
        while (n < _n) n *= 2;
        dat = vector< long long >(2 * n - 1, init);
        lazy = vector< long long >(2 * n - 1, lazy_def);
        width = vector< int >(2 * n - 1);
        width[0] = n;
        repr(i, 1, 2 * n - 1) width[i] = width[(i - 1) / 2] / 2;
    }

    // 区間[a,b)にvを作用させる
    void range_operation(int a, int b, long long v, int k = 0, int l = 0,
                         int r = -1) {
        if (r == -1) r = n;
        if (r <= a || b <= l) return; // 交差しない
        if (a <= l && r <= b) {       // a,l,r,bの順で完全に含まれる
            set_lazy(k, v);
            return;
        }
        push(k);
        range_operation(a, b, v, 2 * k + 1, l, (l + r) / 2); // 左の子
        range_operation(a, b, v, 2 * k + 2, (l + r) / 2, r); // 右の子
        dat[k] = operation(dat[k * 2 + 1], dat[k * 2 + 2]);
    }

    // [a, b)の区間クエリを実行
    long long query(int a, int b) {
        return _query(a, b, 0, 0, n);
    }

    //  添字でアクセス
    long long operator[](int i) {
        return query(i, i + 1);
    }
};

int main(void) {
    int N, Q;
    cin >> N >> Q;
    auto operation = [](ll a, ll b) { return a + b; };
    auto adapt_lazy = [](ll a, ll b) { return b; };
    auto merge_lazy = [](ll a, ll b) { return b; };
    auto multiply_lazy = [](ll a, int n) { return a * n; };
    LazySegTree< ll, ll > lst(N, 0, 0, -INFL, operation, adapt_lazy, merge_lazy,
                              multiply_lazy);

    rep(q, Q) {
        int c;
        cin >> c;
        if (c == 0) {
            // add(s, t, x)
            int s, t, x;
            cin >> s >> t >> x;
            lst.range_operation(s, t + 1, x);
        } else {
            // getSum(s, t)
            int s, t;
            cin >> s >> t;
            cout << lst.query(s, t + 1) << endl;
        }
    }

    return 0;
}


Measured memory_bytes: 7864