#include <bits/stdc++.h>
using namespace std;
long long N, A, B;
vector<long long> vec;
string S;
void solve() {
  bool flag = false;
  for (int i = 0; i < S.size(); i++) {
    if (S[i] >= '0' && S[i] <= '9') {
      continue;
    }
    if (S[i] == '-' && flag == false) {
      flag = true;
      continue;
    }
    cout << "No";
  }
  if (flag == true) {
    cout << "Yes";
  } else {
    cout << "No";
  }
  return;
}
int main() {
  cin >> A >> B >> S;
  solve();
  cout << endl;
  return 0;
}
