View Compilation Error

0_0_28615151_14924.cpp: In function 'int main()':
0_0_28615151_14924.cpp:4:2: error: '_int64' was not declared in this scope
  _int64 a,b,x;
  ^
0_0_28615151_14924.cpp:5:29: error: 'a' was not declared in this scope
  while(scanf("%I64d %I64d",&a,&b)!=EOF)
                             ^
0_0_28615151_14924.cpp:5:32: error: 'b' was not declared in this scope
  while(scanf("%I64d %I64d",&a,&b)!=EOF)
                                ^
0_0_28615151_14924.cpp:9:3: error: 'x' was not declared in this scope
   x=a;
   ^