recursive function debug asserion failed

I try to use recursive function to output all parameters of an int type vector, it works butenter image description here there is a Debug Assertion failed occurred. please help me point out where is problem from. thanks in advance.

#include<iostream>
#include<vector>
using namespace std;
void val(vector<int>::const_iterator beg, vector<int>::const_iterator end)
{
    if (beg!=end)
        cout << *beg << endl;
    
    val((beg + 1),end);
}
int main()
{
    int n;
    vector<int> vec;
    while (cin >> n)
        vec.push_back(n);
    val(vec.begin(),vec.end());
        
}

void val(vector<int>::const_iterator beg, vector<int>::const_iterator end)
{
    if(beg == end) return;

    cout << *beg << endl;
    val(beg + 1,end);
}

void val(vector<int>::const_iterator beg, vector<int>::const_iterator end)
{
    if (beg!=end)
    {
        cout << *beg << endl;
        val((beg + 1),end);
    }
}