#include <bits/stdc++.h>
using namespace std;
int main() {
  int A, B;
  string S;
  cin >> A >> B;
  cin >> S;
  bool pass = true;
  for (int m = 0; m < A; m++) {
    if (!isdigit(S[m])) {
      pass = false;
    }
  }
  if (pass && S[A] == '-') {
    pass = true;
  } else {
    pass = false;
  }
  int counter = A + 1, counter1 = 0;
  if (pass) {
    while (counter1 < B) {
      if (!isdigit(S[counter])) {
        pass = false;
      }
      counter++;
      counter1++;
    }
  }
  if (pass) {
    cout << "yes";
  } else {
    cout << "no";
  }
  return 0;
}
