zoj 1312 Prime Cuts

#include<iostream>using namespace std;int f(int n){    if(n==1||n==2)return 1;    else if(n%2==0)return 0;    else    {        int i,flag=1;        for(i=3;i*i<=n;i+=2) if(n%i==0) {     flag=0;     break; }        if(flag)return 1;        else return 0;    }}int main(){    int n,c,a[1000],i,k;    while(cin>>n>>c)    {        k=1;        for(i=1;i<=n;i++) if(f(i))     a[k++]=i;        k-=1;        cout<<n<<" "<<c<<": ";        if(k%2)        { if(k>2*c-1) {     for(i=(k-2*c+1)/2+1;i<(k-2*c+1)/2+2*c-1;i++)         cout<<a[i]<<" ";     cout<<a[i]<<endl; } else {     for(i=1;i<k;i++)         cout<<a[i]<<" ";     cout<<a[k]<<endl; }        }        else        { if(k>2*c) {     for(i=(k-2*c)/2+1;i<(k-2*c)/2+2*c;i++)         cout<<a[i]<<" ";     cout<<a[i]<<endl; } else {     for(i=1;i<k;i++)         cout<<a[i]<<" ";     cout<<a[k]<<endl; }        }        cout<<endl;    }    return 0;}