View Compilation Error

0_0_33317815_3293.cpp:9:15: error: '_int64' was not declared in this scope
 long long gcd(_int64 m, _int64 n) {
               ^
0_0_33317815_3293.cpp:9:25: error: '_int64' was not declared in this scope
 long long gcd(_int64 m, _int64 n) {
                         ^
0_0_33317815_3293.cpp:9:33: error: expression list treated as compound expression in initializer [-fpermissive]
 long long gcd(_int64 m, _int64 n) {
                                 ^
0_0_33317815_3293.cpp:9:35: error: expected ',' or ';' before '{' token
 long long gcd(_int64 m, _int64 n) {
                                   ^