longest common subsequence by recursion

#include<iostream>
#include<math.h>
#include<cstring>
using namespace std;

int LCS(char str1[],char str2[],int l1,int l2){
  if(l1==0 ||l2==0)
     return 0;
  if(str1[l1-1]==str2[l2-1])
  return 1+LCS(str1,str2,l1-1,l2-1);
  return max(LCS(str1,str2,l1,l2-1),LCS(str1,str2,l1-1,l2));
  }

int main(){
  char X[] = "AGGTAB";
  char Y[] = "GXTXAYB";
  int m = strlen(X);
  int n = strlen(Y);
  cout<<"Length of LCS is "<<LCS( X, Y, m, n ) ;
  return 0;
  }