#include <bits/stdc++.h>
using namespace std;
int A, B;
string S;
int main() {
  cin >> A >> B >> S;
  bool ad = true;
  for (int(i) = 0; (i) < (A); (i)++)
    if (S[i] == '-') ad = false;
  if (S[A] != '-') ad = false;
  for (int(i) = 0; (i) < (B); (i)++)
    if (S[i + A + 1] == '=') ad = false;
  if (ad)
    cout << "Yes";
  else
    cout << "No";
}
