/in/foo.cc:5:12: error: '::main' must return 'int'
 void main (){
            ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:7:2: error: '_int64' was not declared in this scope
  _int64  a,b,c,d; 
  ^~~~~~
/in/foo.cc:8:10: error: expected ';' before 'result'
  _int64  result;//In GNU C++, 64-bit integers MUST be of type "long long"
          ^~~~~~
/in/foo.cc:9:16: error: 'a' was not declared in this scope
 scanf("%I64u",&a);
                ^
/in/foo.cc:11:16: error: 'b' was not declared in this scope
 scanf("%I64u",&b);
                ^
/in/foo.cc:12:16: error: 'c' was not declared in this scope
 scanf("%I64u",&c);
                ^
/in/foo.cc:13:16: error: 'd' was not declared in this scope
 scanf("%I64u",&d);
                ^
/in/foo.cc:14:1: error: 'result' was not declared in this scope
 result=a*d-b*c;
 ^~~~~~