zoj 1760 Doubles

水题～～

#include<iostream>using namespace std;int main(){int num[100],i,sum,x;while(cin>>x,x!=-1){for(i=0;i<100;i++)num[i]=0;sum=0;num[x]++;while(cin>>x,x)num[x]++;for(i=0;i<50;i++)if(num[2*i])sum+=num[i];cout<<sum<<endl;}return 0;}