So what's wrong?

#include <iostream.h>

short a[50000],b[50000],sign[2]={-1,1};

int dist(int a, int b){
    int d=a-b;
    if(d<0)d*=-1;
    return d;
}

int main(){
    int i,j,k=0,t,n,m;
    while(cin>>n){
        for(i=0;i<n;i++)cin>>a[i];
        cin>>m;
        for(j=0;j<m;j++)cin>>b[j];
        for(i=0;i<n;i++){
            k=0;
            j=m-1;
            while(dist(j,k)!=1){
                if(a[i]+b[j]==10000)goto yes;
                else{
                    t=j;
                    j+=sign[a[i]+b[j]>10000]*dist(j,k)/2;
                    k=t;
                }
                if(a[i]+b[j-1]==10000 || a[i]+b[j]==10000 || a[i]+b[j+1]==10000)goto yes;
            }
        }
        cout<<"NO";
        return 0;
yes:
        cout<<"YES";
        return 0;
    }
}