#include <bits/stdc++.h>
#include <boost/multiprecision/cpp_int.hpp>

#define repd(i, a, b) for (ll i = (a); i < (b); i++)
#define rep(i, n) repd(i, 0, n)

using namespace std;

namespace mp = boost::multiprecision;

using ll = long long;
using Bint = mp::cpp_int;
ll mod = pow(10, 9) + 7;

int main() {
    // source
    ll a, b;
    cin >> a >> b;
    string s;
    cin >> s;
    string s_a, s_b;
    s_a = s.substr(0, a);
    s_b = s.substr(a + 1, b);

    bool ans = true;
    rep(i, a) {
        if ('0' > s_a[i] || s_a[i] > '9') {
            ans = false;
        }
    }
    rep(i, b) {
        if ('0' > s_b[i] || s_b[i] > '9') {
            ans = false;
        }
    }

    if (s[a] != '=') {
        ans = false;
    }

    if (ans) {
        cout << "Yes" << endl;
    } else {
        cout << "No" << endl;
    }
    return 0;
}

