View Compilation Error

0_0_16480432_24329.cpp: In function 'int main()':
0_0_16480432_24329.cpp:4:2: error: '_int64' was not declared in this scope
  _int64 m,n;
  ^
0_0_16480432_24329.cpp:5:29: error: 'm' was not declared in this scope
  while(scanf("%I64x %I64x",&m,&n)!=EOF)
                             ^
0_0_16480432_24329.cpp:5:32: error: 'n' was not declared in this scope
  while(scanf("%I64x %I64x",&m,&n)!=EOF)
                                ^