1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
#include "bits/stdc++.h" // Ignacy Boehlke
using namespace std;     // XIII LO Szczecin
auto operator<<(auto&o,auto p)->decltype(p.first,o){return o<<'{'<<p.first<<", "<<p.second<<'}';}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<'{';int i=2;for(auto e:x)o<<(", ")+i<<e,i=0;return o<<'}';}
#ifdef DEBUG
#define PF(x...)fprintf(stderr,x)
#define LOG(x...)cerr<<"["#x"]: ",[](auto...$){((cerr<<$<<"; "),...)<<'\n';}(x)
#else
#define PF(...)(void)0
#define LOG(...)(void)0
#endif
#define FOR(a,b,c)for(int a=(b);a<=(c);++a)
#define REP(a,b)FOR(a,0,(b)-1)
#define ALL(x)(x).begin(), (x).end()
#define fi first
#define se second
using ll=int64_t;

int main() {
        cin.tie(0)->sync_with_stdio(0);
        int H, W, n;
        cin >> H >> W >> n;
        vector<int> a(n);
        REP(i, n) cin >> a[i];

        if (H % a[0] || W % a[0]) {
                cout << "-1\n";
                return 0;
        }

        reverse(ALL(a));
        ll res = 0;
        auto solve = [&](auto &self, int h, int w, int i) {
                if (!h || !w) return;
                assert(i < n);
                int s = a[i];
                if (h < s || w < s) {
                        self(self, h, w, i + 1);
                        return;
                }
                res += (ll)(w / s) * (h / s);
                if (h % s == 0) swap(h, w);
                if (w % s == 0) {
                        self(self, w, h % s, i + 1);
                        return;
                }
                self(self, w % s, h % s, i + 1);
                self(self, w % s, h - h % s, i + 1);
                self(self, w - w % s, h % s, i + 1);
        };
        solve(solve, H, W, 0);
        cout << res << '\n';
}