#!/usr/bin/env python3
def main():
    import numpy as np

    N, K = map(int, input().split())
    S = set()
    for _ in range(K):
        l, r = map(int, input().split())
        for n in range(l, r + 1):
            S.add(n)
    MOD = 998244353

    dp = [0] * N
    dp[0] = 1
    dp = np.zeros(N, dtype=np.int64)
    dp[0] = 1
    for i in range(N):
        for d in S:
            if i >= d:
                dp[i] += dp[i - d] % MOD
    print(dp[-1] % MOD)


if __name__ == '__main__':
    main()
