CF : B. Easy Number Challenge 数论（素数）

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <string>

#define CL(a,num) memset((a),(num),sizeof(a))
#define iabs(x)  ((x) > 0 ? (x) : -(x))
#define Min(a,b) (a) > (b)? (b):(a)
#define Max(a,b) (a) > (b)? (a):(b)

#define ll long long
#define inf 0x7f7f7f7f
#define MOD 1073741824
#define lc l,m,rt<<1
#define rc m + 1,r,rt<<1|1
#define pi acos(-1.0)
#define test puts("<------------------->")
#define maxn 100007
#define M 1000007
#define N 107
using namespace std;

int num[M];
int main()
{
//freopen("data.in","r",stdin);
int i,j,k;
int a,b,c;
while (~scanf("%d%d%d",&a,&b,&c))
{
CL(num,0);
for (i = 1; i < M; ++i)
{
for (j = i; j < M; j += i) num[j]++;
}
ll ans = 0;
for (i = 1; i <= a; ++i)
{
for (j = 1; j <= b; ++j)
{
for (k = 1; k <= c; ++k)
{
ans += num[i*j*k];
ans %= MOD;
}
}
}
cout<<ans<<endl;
}

return 0;
}