View Compilation Error

0_0_33317812_15100.cpp:9:1: error: '_int64' does not name a type
 _int64 gcd(_int64 m, _int64 n) {
 ^
0_0_33317812_15100.cpp: In function 'long long int lcm(long long int, long long int)':
0_0_33317812_15100.cpp:20:28: error: 'gcd' was not declared in this scope
     return ans / gcd(ans, m) * m;
                            ^