/in/foo.cc: In function 'int main()':
/in/foo.cc:11:21: error: lvalue required as increment operand
   for(int i=2;i<x1;1++)
                     ^~
/in/foo.cc:14:6: error: 'i' was not declared in this scope
   if(i==x1)
      ^
/in/foo.cc:22:3: error: expected ';' before '}' token
   }
   ^