HackerRank C++ Strings

In this Problem we have to take input two strings and print length of strings,Concatenation of string and also reverse order of strings

#include <iostream>
#include <string>
using namespace std;
int main()
{

  string a,b;

    cin>>a;
    cin>>b;

    int len1 = a.size();
    int len2 = b.size();

    cout<<len1<<" "<<len2<<endl;

    cout<<a<<b<<endl;

    char c;
    c=a[0];
    a[0]=b[0];
    b[0]=c;

    cout<<a<<" "<<b;

    return 0;
}