#include <bits/stdc++.h>
using namespace std;

const int mod = 998244353;
int n, k;
long long dp[200010];
int l[20], r[20];

int main() {
	scanf("%d%d", &n, &k);
	for (int i = 0; i < k; ++i)
		scanf("%d%d", &l[i], &r[i]);
	dp[1] = 1;
	for (int i = 2; i <= n; ++i) {
		for (int j = 0; j < k; ++j)
			if (l[j] <= i - 1)
				dp[i] = (dp[i] + dp[i - l[j]] - (i - r[j] >= 2 ? dp[i - r[j] - 1] : 0)) % mod;
		dp[i] = (dp[i] + dp[i - 1]) % mod;
	}
	printf("%lld\n", ((dp[n] - dp[n - 1]) % mod + mod) % mod);
	return 0;
}

