#include<bits/stdc++.h>
#define LL __int128
using namespace std;
const int N=1e7;
int pr, p[N+10];LL mu[N+10]; bool v[N+10];
void init()
{
	memset(v,0,sizeof(v));
	pr=0;mu[0]=0;mu[1]=1;
    for(int i=2;i<=N;i++)
	{
        if(!v[i]) p[++pr]=i, mu[i]=-1; 
        for(int j=1;j<=pr&&p[j]*i<=N;j++)
		{
            v[i*p[j]]=true;
            if(i%p[j]==0){mu[i*p[j]]=0;break;}
            mu[i*p[j]]=-mu[i];
        }
    }
    for(int i=1;i<=N;i++) mu[i]+=mu[i-1];
}
LL calc2(int a,int b)
{
    int n=min(a,b);
	LL ans=0;
    for(int l=1,r;l<=n;l=r+1)
	{
        r=min(a/(a/l), b/(b/l));
        ans+=(mu[r]-mu[l-1])*(a/l)*(b/l);
    }
    return ans;
}
LL calc3(int a,int b,int c)
{
    int n=min({a,b,c});
	LL ans=0;
    for(int l=1,r;l<=n;l=r+1)
	{
        r=min({a/(a/l), b/(b/l),c/(c/l)});
        ans+=(mu[r]-mu[l-1])*(a/l)*(b/l)*(c/l);
    }
    return ans;
}
void qr(LL x)
{
	if(x>9)qr(x/10);
	printf("%d",int(x%10));
}
int main()
{
	init();
	int a,b,c;
	while(scanf("%d%d%d",&a,&b,&c)!=EOF)
	{
		if(a==1 && b==1 && c==1) {printf("0\n");continue;}
		a--;b--;c--;
        qr(calc3(a,b,c)+calc2(a,b)+calc2(a,c)+calc2(b,c)+3);
        printf("\n");
	}
    return 0;
}