#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
long long powmod(long long a, long long b) {
  long long res = 1;
  a %= mod;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % mod;
    a = a * a % mod;
  }
  return res;
}
long long gcd(long long a, long long b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
int lcm(int a, int b) { return abs(a * b) / gcd(a, b); }
int digit(int n) {
  int sum = 0;
  while (n != 0) {
    sum += n % 10;
    n = n / 10;
  }
  return sum;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  string s;
  int a, b;
  cin >> a >> b;
  cin >> s;
  for (int i = 0; i < a; ++i) {
    if (!(s[i] >= '0' && s[i] <= '9')) {
      cout << "No";
      exit(0);
    }
  }
  for (int i = a + 1; i <= a + b; ++i) {
    if (!(s[i] >= '0' && s[i] <= '9')) {
      cout << "No";
      exit(0);
    }
  }
  cout << "Yes";
}
