// Template
#include <bits/stdc++.h>
#define rep_override(x, y, z, name, ...) name
#define rep2(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep3(i, l, r) for (int i = (int)(l); i < (int)(r); ++i)
#define rep(...) rep_override(__VA_ARGS__, rep3, rep2)(__VA_ARGS__)
#define per(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define all(x) (x).begin(), (x).end()
using namespace std;
using ll = long long;
constexpr int inf = 1001001001;
constexpr ll INF = 3003003003003003003LL;
template <typename T> inline bool chmin(T &x, const T &y) {if (x > y) {x = y; return 1;} return 0;}
template <typename T> inline bool chmax(T &x, const T &y) {if (x < y) {x = y; return 1;} return 0;}
struct IOSET {IOSET() {cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(10);}} ioset;

// Mod-Int
constexpr int MOD = 998244353;
struct ModInt {
    ll val;
    ModInt() = default;
    ModInt(ll x) : val(x % MOD + (x < 0 ? MOD : 0)) {}
    ModInt &operator+= (const ModInt &x) {if ((val += x.val) >= MOD) val -= MOD; return *this;}
    ModInt &operator-= (const ModInt &x) {if ((val -= x.val) < 0) val += MOD; return *this;}
    ModInt &operator*= (const ModInt &x) {(val *= x.val) %= MOD; return *this;}
    ModInt operator+ (const ModInt &x) const {return ModInt(*this) += x;}
    ModInt operator- (const ModInt &x) const {return ModInt(*this) -= x;}
    ModInt operator* (const ModInt &x) const {return ModInt(*this) *= x;}
    ModInt pow(ll t) const {
        if (!t) return ModInt(1);
        ModInt m = pow(t / 2);
        m *= m;
        if (t & 1) m *= *this;
        return m;
    }
    ModInt inv() const {return pow(MOD - 2);}
    ModInt &operator/= (const ModInt &x) {return *this *= x.inv();}
    ModInt operator/ (const ModInt &x) const {return ModInt(*this) /= x;}
    friend istream &operator>> (istream &is, ModInt &x) {is >> x.val; return is;}
    friend ostream &operator<< (ostream &os, const ModInt &x) {os << x.val; return os;}
};

// Lazy Segment Tree
template <typename Operator>
class LazySegmentTree {
    Operator OP;
    using NodeType = decltype(OP.NodeE);
    using FuncType = decltype(OP.FuncE);
    int length, height;
    vector<NodeType> node;
    vector<FuncType> lazy;
    vector<int> width;
    void eval(int n) {
        node[n] = OP.NodeFunc(node[n], lazy[n], width[n]);
        if (n < length) {
            lazy[(n << 1) | 0] = OP.MergeFunc(lazy[(n << 1) | 0], lazy[n]);
            lazy[(n << 1) | 1] = OP.MergeFunc(lazy[(n << 1) | 1], lazy[n]);
        }
        lazy[n] = OP.FuncE;
    }
public:
    LazySegmentTree(int n) {
        length = 1;
        height = 0;
        while (length < n) {
            length <<= 1;
            ++height;
        }
        node.resize(length << 1, OP.NodeE);
        lazy.resize(length << 1, OP.FuncE);
        width.resize(length << 1, 1);
        for (int i = length - 1; i > 0; --i) width[i] = width[i << 1] << 1;
    }
    LazySegmentTree(vector<NodeType> &vec) {
        length = 1;
        height = 0;
        while (length < vec.size()) {
            length <<= 1;
            ++height;
        }
        node.resize(length << 1, OP.NodeE);
        rep(i, vec.size()) node[i + length] = vec[i];
        for (int i = length - 1; i > 0; --i) node[i] = OP.MergeNode(node[(i << 1) | 0], node[(i << 1) | 1]);
        lazy.resize(length << 1, OP.FuncE);
        width.resize(length << 1, 1);
        for (int i = length - 1; i > 0; --i) width[i] = width[i << 1] << 1;
    }
    void update(int a, int b, FuncType x) {
        int l = a + length, r = b + length - 1;
        for (int i = height; i > 0; --i) {
            eval(l >> i);
            eval(r >> i);
        }
        ++r;
        while (r > l) {
            if (l & 1) {
                lazy[l] = OP.MergeFunc(lazy[l], x);
                eval(l);
                ++l;
            }
            if (r & 1) {
                --r;
                lazy[r] = OP.MergeFunc(lazy[r], x);
                eval(r);
            }
            l >>= 1; r >>= 1;
        }
        l = a + length; r = b + length - 1;
        while (l >>= 1) node[l] = OP.MergeNode(OP.NodeFunc(node[(l << 1) | 0], lazy[(l << 1) | 0], width[(l << 1) | 0]), OP.NodeFunc(node[(l << 1) | 1], lazy[(l << 1) | 1], width[(l << 1) | 1]));
        while (r >>= 1) node[r] = OP.MergeNode(OP.NodeFunc(node[(r << 1) | 0], lazy[(r << 1) | 0], width[(r << 1) | 0]), OP.NodeFunc(node[(r << 1) | 1], lazy[(r << 1) | 1], width[(r << 1) | 1]));
    }
    NodeType get(int a, int b) {
        int l = a + length, r = b + length - 1;
        for (int i = height; i >= 0; --i) {
            eval(l >> i);
            eval(r >> i);
        }
        ++r;
        NodeType vl = OP.NodeE, vr = OP.NodeE;
        while (l < r) {
            if (l & 1) {
                vl = OP.MergeNode(vl, OP.NodeFunc(node[l], lazy[l], width[l]));
                ++l;
            }
            if (r & 1) {
                --r;
                vr = OP.MergeNode(OP.NodeFunc(node[r], lazy[r], width[r]), vr);
            }
            l >>= 1; r >>= 1;
        }
        return OP.MergeNode(vl, vr);
    }
};
struct RSQ {
    using NodeType = ModInt;
    using FuncType = ModInt;
    NodeType NodeE = ModInt(0);
    FuncType FuncE = ModInt(0);
    NodeType MergeNode(NodeType x, NodeType y) {
        return x + y;
    }
    FuncType MergeFunc(FuncType x, FuncType y) {
        return x + y;
    }
    NodeType NodeFunc(NodeType x, FuncType y, int len) {
        return x + y * ModInt(len);
    }
};

// Main
int main() {
    int n, k;
    cin >> n >> k;
    vector<int> l(k), r(k);
    rep(i, k) cin >> l[i] >> r[i];
    
    LazySegmentTree<RSQ> st(3 * n);
    st.update(0, 1, ModInt(1));
    rep(i, n) {
        auto x = st.get(i, i + 1);
        rep(j, k) {
            st.update(i + l[j], i + r[j] + 1, x);
        }
    }
    
    cout << st.get(n - 1, n) << "\n";
}


Measured memory_bytes: 44124