#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  string s;
  cin >> a >> b >> s;
  bool postal = true;
  if (s[a] != '-') postal = false;
  for (int i = 0; i < a + b + 1; i++) {
    if ((s[i] == '0' || s[i] == '1' || s[i] == '2' || s[i] == '3' ||
         s[i] == '4' || s[i] == '5' || s[i] == '6' || s[i] == '7' ||
         s[i] == '8' || s[i] == '9') or
        i == a)
      continue;
    else
      postal = false;
  }
  postal ? cout << "yes" : cout << "no";
}
