import sys
 
 
def main():
 
    input = sys.stdin.readline
 
    N,K = map(int,input().split())
 
    S = set()
 
    mod = 998244353
 
    for i in range(K):
        l,r = map(int,input().split())
 
        for i in range(l,r+1):
            S.add(i)
 
    masu = [0] * N
 
    masu[0] = 1
 
    for i in range(N):
        for j in S:
            if i+j < N:
                masu[i+j] += masu[i]
                masu[i+j] %= mod
 
    print(masu[N-1] % mod)
    
 
if __name__ == "__main__":
    main()