#include <bits/stdc++.h>
#pragma GCC target("avx")
#pragma GCC optimize(3)
#pragma GCC optimize("Ofast")
#pragma GCC optimize("inline")
#pragma GCC optimize("-fgcse")
#pragma GCC optimize("-fgcse-lm")
#pragma GCC optimize("-fipa-sra")
#pragma GCC optimize("-ftree-pre")
#pragma GCC optimize("-ftree-vrp")
#pragma GCC optimize("-fpeephole2")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-fsched-spec")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-falign-jumps")
#pragma GCC optimize("-falign-loops")
#pragma GCC optimize("-falign-labels")
#pragma GCC optimize("-fdevirtualize")
#pragma GCC optimize("-fcaller-saves")
#pragma GCC optimize("-fcrossjumping")
#pragma GCC optimize("-fthread-jumps")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-fwhole-program")
#pragma GCC optimize("-freorder-blocks")
#pragma GCC optimize("-fschedule-insns")
#pragma GCC optimize("inline-functions")
#pragma GCC optimize("-ftree-tail-merge")
#pragma GCC optimize("-fschedule-insns2")
#pragma GCC optimize("-fstrict-aliasing")
#pragma GCC optimize("-fstrict-overflow")
#pragma GCC optimize("-falign-functions")
#pragma GCC optimize("-fcse-skip-blocks")
#pragma GCC optimize("-fcse-follow-jumps")
#pragma GCC optimize("-fsched-interblock")
#pragma GCC optimize("-fpartial-inlining")
#pragma GCC optimize("no-stack-protector")
#pragma GCC optimize("-freorder-functions")
#pragma GCC optimize("-findirect-inlining")
#pragma GCC optimize("-fhoist-adjacent-loads")
#pragma GCC optimize("-frerun-cse-after-loop")
#pragma GCC optimize("inline-small-functions")
#pragma GCC optimize("-finline-small-functions")
#pragma GCC optimize("-ftree-switch-conversion")
#pragma GCC optimize("-foptimize-sibling-calls")
#pragma GCC optimize("-fexpensive-optimizations")
#pragma GCC optimize("-funsafe-loop-optimizations")
#pragma GCC optimize("inline-functions-called-once")
#pragma GCC optimize("-fdelete-null-pointer-checks")
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
#pragma GCC target( \
    "sse,sse2,sse3,ssse3,sse4.1,sse4.2,avx,avx2,popcnt,tune=native")
using namespace std;
namespace _c {
const double pi = acos(-1.0);
namespace min {
const int i8 = -128;
const int i16 = -32768;
const int i = -2147483647 - 1;
const long long l = -9223372036854775807LL - 1;
}  // namespace min
namespace max {
const int i8 = 127;
const int i16 = 32767;
const int i = 2147483647;
const long long l = 9223372036854775807LL;
}  // namespace max
}  // namespace _c
namespace _f {
template <typename T>
inline const T gcd(T m, T n) {
  while (n != 0) {
    T t = m % n;
    m = n;
    n = t;
  }
  return m;
}
template <typename T>
inline const T max(const T &a, const T &b) {
  return a > b ? a : b;
}
template <typename T>
inline const T min(const T &a, const T &b) {
  return a < b ? a : b;
}
template <typename T>
inline const T abs(const T &a) {
  return a > 0 ? a : -a;
}
template <typename T>
inline T pow(T a, T b) {
  T res = 1;
  while (b > 0) {
    if (b & 1) {
      res = res * a;
    }
    a = a * a;
    b >>= 1;
  }
  return res;
}
template <typename T>
inline T pow(T a, T b, const T &m) {
  a %= m;
  T res = 1;
  while (b > 0) {
    if (b & 1) {
      res = res * a % m;
    }
    a = a * a % m;
    b >>= 1;
  }
  return res % m;
}
}  // namespace _f
namespace io {
template <typename T>
inline void read(T &t) {
  register T res = 0, neg = 1;
  char g = getchar();
  for (; !isdigit(g); g = getchar()) {
    if (g == '-') {
      neg = -1;
    }
  }
  for (; isdigit(g); g = getchar()) {
    res = res * 10 + g - '0';
  }
  t = res * neg;
}
inline int in() {
  register int T;
  read(T);
  return T;
}
inline long long in_ll() {
  register long long T;
  read(T);
  return T;
}
}  // namespace io
const int M = 2005;
unsigned mu[M], f[M], g[M];
int a, b, c;
int main() {
  for (int i = mu[1] = 1; i < M; ++i) {
    if (mu[i]) {
      for (int j = i + i; j < M; j += i) {
        mu[j] -= mu[i];
      }
    }
  }
  for (int i = 1; i < M; ++i) {
    for (int j = 1; j <= i; ++j) {
      g[i] += i / j;
    }
  }
  io::read(a), io::read(b), io::read(c);
  unsigned ans = 0;
  for (int k = 1; k <= c; ++k) {
    memset((f), 0, sizeof((f)));
    for (int d = 1; d <= k; ++d) {
      if (k % d == 0 and mu[d]) {
        for (int i = 1; i < M; ++i) {
          f[i] += mu[d] * g[i / d];
        }
      }
    }
    unsigned res = 0;
    for (int d = 1; d < M; ++d) {
      if (mu[d] and _f::gcd(k, d) == 1) {
        res += mu[d] * f[a / d] * f[b / d];
      }
    }
    ans += c / k * res;
  }
  printf("%u\n", ans & 1073741823);
  return 0;
}
