#include "bits/stdc++.h" #pragma GCC optimize("Ofast") // Begin Header {{{ #pragma region using namespace std; #ifndef DEBUG #define dump(...) #endif #define all(x) begin(x), end(x) #define rall(x) rbegin(x), rend(x) #define rep(i, b, e) for (intmax_t i = (b), i##_limit = (e); i < i##_limit; ++i) #define repc(i, b, e) for (intmax_t i = (b), i##_limit = (e); i <= i##_limit; ++i) #define repr(i, b, e) for (intmax_t i = (b), i##_limit = (e); i >= i##_limit; --i) #define var(Type, ...) \ Type __VA_ARGS__; \ input(__VA_ARGS__) #define let const auto constexpr size_t operator""_zu(unsigned long long value) { return value; }; constexpr intmax_t operator""_jd(unsigned long long value) { return value; }; constexpr uintmax_t operator""_ju(unsigned long long value) { return value; }; constexpr int INF = 0x3f3f3f3f; constexpr intmax_t LINF = 0x3f3f3f3f3f3f3f3f_jd; using usize = size_t; using imax = intmax_t; using uimax = uintmax_t; using ld = long double; template > using MaxHeap = priority_queue, Compare>; template > using MinHeap = priority_queue, Compare>; inline void input() {} template inline void input(Head&& head, Tail&&... tail) { cin >> head; input(forward(tail)...); } template ::value, nullptr_t> = nullptr> inline istream& operator>>(istream& is, Container& vs) { for (auto& v: vs) is >> v; return is; } template inline istream& operator>>(istream& is, pair& p) { is >> p.first >> p.second; return is; } inline void output() { cout << "\n"; } template inline void output(Head&& head, Tail&&... tail) { cout << head; if (sizeof...(tail)) cout << " "; output(forward(tail)...); } template ::value, nullptr_t> = nullptr> inline ostream& operator<<(ostream& os, const Container& vs) { static constexpr const char* delim[] = {" ", ""}; for (auto it = begin(vs); it != end(vs); ++it) { os << delim[it == begin(vs)] << *it; } return os; } template inline void join(const Iterator& Begin, const Iterator& End, const string& delim = "\n", const string& last = "\n") { for (auto it = Begin; it != End; ++it) { cout << ((it == Begin) ? "" : delim) << *it; } cout << last; } template inline vector makeVector(const T& init_value, size_t sz) { return vector(sz, init_value); } template inline auto makeVector(const T& init_value, size_t sz, Args... args) { return vector(init_value, args...))>( sz, makeVector(init_value, args...)); } template class FixPoint : Func { public: explicit constexpr FixPoint(Func&& f) noexcept : Func(forward(f)) {} template constexpr decltype(auto) operator()(Args&&... args) const { return Func::operator()(*this, std::forward(args)...); } }; template static inline constexpr decltype(auto) makeFixPoint(Func&& f) noexcept { return FixPoint {forward(f)}; } template struct reverse_t { Container& c; reverse_t(Container& c) : c(c) {} auto begin() { return c.rbegin(); } auto end() { return c.rend(); } }; template auto reversed(Container& c) { return reverse_t(c); } template inline bool chmax(T& a, const T& b) noexcept { return b > a && (a = b, true); } template inline bool chmin(T& a, const T& b) noexcept { return b < a && (a = b, true); } template inline T diff(const T& a, const T& b) noexcept { return a < b ? b - a : a - b; } template inline T sigma(const T& l, const T& r) noexcept { return (l + r) * (r - l + 1) / 2; } template inline T ceildiv(const T& n, const T& d) noexcept { return (n + d - 1) / d; } void operator|=(vector::reference lhs, const bool rhs) { lhs = lhs | rhs; } void operator&=(vector::reference lhs, const bool rhs) { lhs = lhs & rhs; } void operator^=(vector::reference lhs, const bool rhs) { lhs = lhs ^ rhs; } void ioinit() { ios_base::sync_with_stdio(false); cin.tie(nullptr); cout << fixed << setprecision(10); cerr << fixed << setprecision(10); clog << fixed << setprecision(10); } #pragma endregion // }}} End Header int main() { ioinit(); var(intmax_t, A, B, S); intmax_t res = 0; for (intmax_t x = 1; x <= A; ++x) { for (intmax_t y = 1; y <= B; ++y) { if (x * y > S) break; res += (A - x + 1) * (B - y + 1); } } output(res); return 0; }