function Main(input) {
    input = input.split("\n");
    const N = Number(input[0]);
    const A = input[1].trim().split("").map(Number);

    while (A.length && A.at(-1) == 0) A.pop();
    let i = 0;
    while (i < A.length && A[i] === 1) i++;
    A.push(0);

    let ans = 1;
    let mod = 998244353;
    let cnt = 1;

    while (i < A.length - 1) {
        cnt++;
        if (A[i] - A[i + 1] > 0) {
            ans *= cnt;
            ans %= mod;
            cnt = 1;
        }
        i++;
    }
    console.log(ans)
}
Main(require("fs").readFileSync(0)+"")