#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  string s;
  cin >> a >> b;
  cin >> s;
  string s1, s2, s3;
  bool flag = true;
  s1 = s.substr(0, a - 1);
  s2 = s.substr(a, 1);
  s3 = s.substr(a + 1, a + b);
  s1 += s3;
  int i = 0;
  while (flag && i < a + b) {
    if (48 > s1[i] || s1[i] > 57) flag = false;
    i++;
  }
  if (s2[0] != 45) flag = false;
  if (flag)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
