View Compilation Error

0_0_32916760_25318.cpp: In function 'int main()':
0_0_32916760_25318.cpp:23:34: error: 'gcd' was not declared in this scope
     if(m <= n && m > 0 && gcd(n,m) == (n^m))
                                  ^
0_0_32916760_25318.cpp:28:35: error: 'gcd' was not declared in this scope
      if(m <= n && m > 0 && gcd(n,m) == (n^m))
                                   ^