#include <bits/stdc++.h>
using namespace std;
int n, m;
int main() {
  int a, b;
  cin >> a >> b;
  char s[13];
  cin >> s;
  int f = 0;
  for (int i = 0; s[i]; i++) {
    if (s[i] >= '0' && s[i] <= '9')
      continue;
    else if (s[i] == '-')
      f++;
    else
      f++;
  }
  if (f > 1 || f == 0)
    puts("No");
  else
    puts("Yes");
  return 0;
}
