#include <bits/stdc++.h>
constexpr double PI = 3.141592653589793;
constexpr long long INF = 1e18 + 10;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
using namespace std;
vector<pair<long long, long long>> primeFactorize(long long N) {
  vector<pair<long long, long long>> res;
  for (long long a = 2; a * a <= N; ++a) {
    if (N % a != 0) continue;
    long long ex = 0;
    while (N % a == 0) {
      ++ex;
      N /= a;
    }
    res.push_back({a, ex});
  }
  if (N != 1) res.push_back({N, 1});
  return res;
}
int main() {
  ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  int a, b;
  string s;
  cin >> a >> b >> s;
  if (s[a] != '-') {
    cout << "No"
         << "\n";
    return 0;
  }
  for (int i = 0; i < a + b + 1; i++) {
    if (i == a) {
      continue;
    }
    int p = s[i] - 'a';
    if (p < 0 || 26 < p) {
      cout << "No"
           << "\n";
      return 0;
    }
  }
  cout << "Yes"
       << "\n";
  return 0;
}
