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

#define MOD 998244353

int n;
int k;
int l[10], r[10];
long long memo[200005];

int main() {
	scanf("%d%d", &n, &k);
	for (int i = 0; i < k; i++) {
		scanf("%d%d", &l[i], &r[i]);
	}
	memo[1] = 1;
	for (int i = 2; i <= n; i++) {
		memo[i] = memo[i - 1];
		for (int j = 0; j < k; j++) {
			memo[i] += memo[max(0, i - l[j])] - memo[max(0, i - r[j] - 1)];
			memo[i] = (memo[i] + MOD) % MOD;
		}
	}
	printf("%lld\n", (memo[n] - memo[n - 1] + MOD) % MOD);
	return 0;
}
