#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  string s;
  cin >> a >> b >> s;
  bool flag = true;
  if (s[a] == '-') {
    string front = s.substr(0, a);
    string back = s.substr(b);
    for (int i = 0; i < front.size(); i++) {
      if (('0' > front[i] && front[i] > '9') || front[i] == '-') {
        flag = false;
      }
    }
    for (int i = 0; i < back.size(); i++) {
      if (('0' > back[i] && back[i] > '9') || back[i] == '-') {
        flag = false;
      }
    }
  } else
    flag = false;
  if (flag)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
