#include<iostream>
using namespace std;
int main(){
int N=10,k=-1,mid,high=N-1,low=0,m;
int a[N]={-3,4,7,9,13,45,67,89,100,180};
cout<<"输入所选的值"<<endl;
cin>>m;
while(low<=high){
mid=(low+high)/2;
if(m<a[mid]){
high=mid-1;
}
if(m>a[mid]){
low=mid+1;
}
if(m==a[mid]){
k=mid;
break;
}
}
if(k>=0){
cout<<k<<endl;}
else{
cout<<"not be found"<<endl;
}
return 0;
}
