#include <bits/stdc++.h>
using namespace std;
template <typename T>
void MACRO_VAR_Scan(T& t) {
  cin >> t;
}
template <typename First, typename... Rest>
void MACRO_VAR_Scan(First& first, Rest&... rest) {
  cin >> first;
  MACRO_VAR_Scan(rest...);
}
template <typename T>
void MACRO_VEC_ROW_Init(int n, T& t) {
  t.resize(n);
}
template <typename First, typename... Rest>
void MACRO_VEC_ROW_Init(int n, First& first, Rest&... rest) {
  first.resize(n);
  MACRO_VEC_ROW_Init(n, rest...);
}
template <typename T>
void MACRO_VEC_ROW_Scan(int p, T& t) {
  cin >> t[p];
}
template <typename First, typename... Rest>
void MACRO_VEC_ROW_Scan(int p, First& first, Rest&... rest) {
  cin >> first[p];
  MACRO_VEC_ROW_Scan(p, rest...);
}
void _main();
signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  _main();
}
inline long long toInt(std::string s) {
  long long v;
  std::istringstream sin(s);
  sin >> v;
  return v;
}
template <class T>
inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
template <typename A, typename B>
inline void chmin(A& a, B b) {
  if (a > b) a = b;
}
template <typename A, typename B>
inline void chmax(A& a, B b) {
  if (a < b) a = b;
}
long long qp(long long a, long long b) {
  long long ans = 1ll;
  do {
    if (b & 1) ans = 1ll * ans * a;
    a = 1ll * a * a;
  } while (b >>= 1);
  return ans;
}
long long qpmod(long long a, long long b, long long mo) {
  long long ans = 1ll;
  do {
    if (b & 1) ans = 1ll * ans * a % mo;
    a = 1ll * a * a % mo;
  } while (b >>= 1);
  return ans;
}
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
inline bool valid(int x, int h) { return 0 <= x && x < h; }
const double EPS = 1e-8;
const double PI = acos(-1.0);
const int INF = (int)(1e9) + 7;
const long long MOD = (long long)(1e9) + 7;
const long long MOD2 = (long long)(1e18) + 9;
const long long INF2 = (long long)(1e18);
const long long INTMAX = (0x7FFFFFFFL);
const long long LLMAX = (0x7FFFFFFFFFFFFFFFL);
const int N4 = (int)1e4 + 10;
const int N5 = (int)1e5 + 10;
int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
int dy[8] = {0, 1, 0, -1, -1, -1, 1, 1};
long long ans, cnt, ret, cur, f;
void _main() {
  int a, b;
  MACRO_VAR_Scan(a, b);
  ;
  string s;
  MACRO_VAR_Scan(s);
  ;
  if (s[a] == '-') {
    s[a] = ' ';
    f = 1;
    for (int i = (0); i < (a); ++i) f &= (0 <= s[i] - '0' && s[i] - '0' <= 9);
    for (int i = (a + 1); i < (b + 1); ++i)
      f &= (0 <= s[i] - '0' && s[i] - '0' <= 9);
  }
  cout << (f ? "Yes" : "No") << endl;
  ;
}
