#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll INF = 1e18;
const ll mod = 1000000007;
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
int ctoi(char c) {
  if (c >= '0' && c <= '9') {
    return c - '0';
  }
  return 0;
}
ll factorial(ll n) {
  if (n == 1) {
    return 1;
  }
  ll ans = factorial(n - 1);
  return ans * n;
}
ll gcd(ll a, ll b) {
  if (a < b) {
    ll tmp = a;
    a = b;
    b = tmp;
  }
  ll r = a % b;
  while (r != 0) {
    a = b;
    b = r;
    r = a % b;
  }
  return b;
}
ll lcm(ll a, ll b) { return (a / gcd(a, b)) * b; }
int main() {
  ll a, b;
  string s;
  cin >> a >> b >> s;
  string ans = "Yes";
  for (int i = 0; i < (int)(a + b + 1); i++) {
    if (i == a) {
      if (s.at(i) != '-') ans = "No";
    } else {
      ll n = ctoi(s.at(i));
      if (n < 0 || 9 < n) ans = "No";
    }
  }
  cout << ans << endl;
}
