杭电5567

#include <iostream>#include <cstdio>#include <cmath>using namespace std;int main(){int n,b,c,i,j,sum;int a[110];while(~scanf("%d%d%d",&n,&b,&c)){sum=0;for(i=1;i<=n;i++)cin>>a[i];for(i=1;i<n;i++){for(j=i+1;j<=n;j++){if(abs(a[i]-a[j])%b==c)sum++;}}cout<<sum<<endl;}return 0;}