#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  int flag = 0, tc, a, b, i;
  cin >> a >> b >> s;
  for (i = 0; i < a; i++)
    if (!isdigit(s[i])) flag = 1;
  if (s[i] != '-') flag = 1;
  for (i++; i < b; i++)
    if (!isdigit(s[i])) flag = 1;
  cout << (flag ? "No\n" : "Yes\n");
}
