UVA 10791 Minimum Sum LCM

#include<stdio.h>
#include<math.h>
#include<string.h>
#define LL long long
const int maxn=100000;
int pri[maxn],vis[maxn];
void getpri()
{
    int i,j,k;
    for(i=2;i*i<maxn;i++)if(!vis[i])
        for(j=i*i;j<maxn;j+=i)vis[j]=1;
    for(i=2,j=0;i<maxn;i++)if(!vis[i])
        pri[j++]=i;
}
LL calcu(int n)
{
    int i,j,k,tmp;
	long long ans=0;
    int sqr=sqrt(n+0.5);
    for(i=0;pri[i]<=sqr;i++)
    if(n%pri[i]==0)
    {
        tmp=1;
        while(n%pri[i]==0)
        {
            n/=pri[i];
            tmp*=pri[i];
        }
        ans+=tmp;
        if(n==1)break;
    }
    if(n>1)ans+=n;
    return ans;
}
int main()
{
    int i,j,n,k=1;
    printf("%d\n",(1<<31)-1);
    getpri();
    while(scanf("%d",&n)!=-1&&n)
    {
        printf("Case %d: ",k++);
        LL ans=calcu(n);
        if(ans==n)ans++;
        if(n==1)ans=2;
        printf("%lld\n",ans);
    }
    return 0;
}