求助，全是WA

#include<iostream>
#include<algorithm>
using namespace std;
int main() {
    int m,n;
    cin>>m>>n;
    int *a=new int[m+1];
    int *b=new int[n];
    for(int i=1; i<=m; i++)
        cin>>a[i];
    for(int i=0; i<n; i++)
        cin>>b[i];
    for(int i=0; i<n;i++) {
        int ans=lower_bound(a+1,a+1+m,b[i])-a;
        if(a[ans]!=b[i])
            cout<<-1;
        else cout<<ans;
        if(i!=n-1)
        cout<<ends;
    }
    delete[] a;
    delete[] b;
    return 0;
}