foo.cpp: In function 'int gcd(int64, int64)':
foo.cpp:14:24: error: new declaration 'int gcd(int64, int64)'
 int gcd(int64 x,int64 y)
                        ^
foo.cpp:5:7: error: ambiguates old declaration 'int64 gcd(int64, int64)'
 int64 gcd(int64 x,int64 y);
       ^
foo.cpp: In function 'int lcm(int64, int64)':
foo.cpp:27:24: error: new declaration 'int lcm(int64, int64)'
 int lcm(int64 x,int64 y)
                        ^
foo.cpp:6:7: error: ambiguates old declaration 'int64 lcm(int64, int64)'
 int64 lcm(int64 x,int64 y);
       ^