#include "bits/stdc++.h"

#ifdef WINT_MIN
#define __MAI
#endif

using namespace std;
typedef unsigned int uint;
typedef long long int ll;
typedef unsigned long long int ull;

#define debugv(v) printf("L%d %s => ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;
#define debugm(m) printf("L%d %s is..\n",__LINE__,#m);for(auto v:m){for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) printf("L%d %s is => ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;
#define debugaa(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[x][y]<<" ";}cout<<endl;}
#define debugaar(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}
#define ALL(v) (v).begin(),(v).end()
#define repeat(l) for(auto cnt=0;cnt<(l);++cnt)
#define upto(l,r) for(auto cnt=l;cnt<=r;++cnt)
#define downto(r,l) for(auti cnt=r;cnt>=l;--cnt)
#define BIGINT 0x7FFFFFFF
#define MD 1000000007ll
#define PI 3.1415926535897932384626433832795
void printbit(int u) { if (u == 0)cout << 0; else { int s = 0, k = 0; for (; 0<u; u >>= 1, k++)s = (s << 1) | (u & 1); for (; 0<k--; s >>= 1)cout << (s & 1); } }template<typename T1, typename T2>
    ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << "(" << p.first << ":" << p.second << ")"; return o; }

#define TIME chrono::system_clock::now()
#define MILLISEC(t) (chrono::duration_cast<chrono::milliseconds>(t).count())

namespace {
    std::chrono::system_clock::time_point t;
    void tic() { t = TIME; }
    void toc() { fprintf(stderr, "TIME : %lldms\n", MILLISEC(TIME - t)); }
    std::chrono::system_clock::time_point tle = TIME;
#ifdef __MAI
    void safe_tle(int msec) { assert(MILLISEC(TIME - tle) < msec); }
#else
#define safe_tle(k) ;
#endif
}

#ifndef __MAI 
namespace {
    class MaiScanner {
    public:
        template<typename T>
        void input_integer(T& var) {
            var = 0;
            T sign = 1;
            int cc = getchar_unlocked();
            for (; cc<'0' || '9'<cc; cc = getchar_unlocked())
                if (cc == '-') sign = -1;
            for (; '0' <= cc&&cc <= '9'; cc = getchar_unlocked())
                var = (var << 3) + (var << 1) + cc - '0';
            var = var*sign;
        }
        void ign() { getchar_unlocked(); }
        MaiScanner& operator>>(int& var) {
            input_integer<int>(var);
            return *this;
        }
        MaiScanner& operator>>(long long& var) {
            input_integer<long long>(var);
            return *this;
        }
    };
}
MaiScanner scanner;
#else
#define scanner cin
#endif

int width, height;
int m, n, kei;

double xx, yy;

double aa[100];

int main() {
    int i, j, k;
    int x, y, z, a, b;

    scanner >> x >> y;
    xx = x;
    yy = y;

    scanner >> n;

    repeat(n) {
        scanner >> a;
        aa[cnt] = a;
    }

    double dist = aa[0];
    for (i = 1; i < n; ++i) {
        double time = aa[i] / y;
        double koba = time * x;
        if (koba < aa[i - 1]) {
            cout << "NO" << endl;
            return 0;
        }
    }
    cout << "YES" << endl;




    return 0;
}