Converting string and int for using stringstream

#include<bits/stdc++.h>
using namespace std;
#define ll long long


string int_to_str(int n)
{
    stringstream ss;
    ss<<n;
    return ss.str();
}

int str_to_int(string s)
{
    stringstream ss(s);
    int n;
    ss>>n;
    return n;
}
int main()
{
    ios_base::sync_with_stdio(0);
    string s;
    cout<<"Input string : ";
    cin>>s;
    int n;
    cout<<"Input integer : ";
    cin>>n;
    int m=str_to_int(s);
    string p=int_to_str(n);
    cout<<"String to integer convert: "<<m<<endl;
    cout<<"Integer to string convert: "<<p<<endl;
}