#include <bits/stdc++.h>
int main() {
  int a, b;
  scanf("%d %d", &a, &b);
  getchar();
  char str[a + b + 1];
  scanf("%s", &str);
  int length = strlen(str);
  int flag = 0;
  for (int i = 0; i < length; i++) {
    if (str[i] >= '0' && str[i] <= '9') {
      continue;
    } else if ('0' > str[i] || str[i] > '9') {
      if (i == a) {
        flag = 1;
        continue;
      } else if (i != a) {
        flag = 0;
        break;
      }
    }
  }
  if (flag = 1) {
    printf("Yes\n");
  }
  if (flag = 0) {
    printf("No\n");
  }
  return 0;
}
