View Compilation Error

0_0_28333473_11446.cpp: In function 'int main()':
0_0_28333473_11446.cpp:4:1: error: '_int64' was not declared in this scope
 _int64 a,b;
 ^
0_0_28333473_11446.cpp:5:28: error: 'a' was not declared in this scope
 while(scanf("%I64X %I64X",&a,&b)!=EOF)
                            ^
0_0_28333473_11446.cpp:5:31: error: 'b' was not declared in this scope
 while(scanf("%I64X %I64X",&a,&b)!=EOF)
                               ^