Longest Common Sub-Sequence By Recursion

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

int lcs(string s1, string s2, int i, int j)
{
    if(i == s1.size() || j == s2.size())
        return 0;

    else if(s1[i] == s2[j])
        return 1 + lcs(s1, s2, i+1, j+1);

    else
        return max(lcs(s1, s2, i+1, j),  lcs(s1, s2, i, j+1));
}

int main()
{
    string s1, s2;

    cout << "Enter First String :: ";
    cin >> s1;

    cout << "Enter Second String :: ";
    cin >> s2;

    cout << endl << "Longest Common Sub-Sequence Size is :: ";
    cout << lcs(s1, s2, 0, 0) << endl;

    return 0;
}