/in/foo.cc: In function 'int main()':
/in/foo.cc:8:10: error: expected initializer before 'b'
  float a b s;
          ^
/in/foo.cc:9:7: error: 'a' was not declared in this scope
  cin>>a;
       ^
/in/foo.cc:10:7: error: 'b' was not declared in this scope
  cin>>b;
       ^
/in/foo.cc:11:2: error: 's' was not declared in this scope
  s=a+a*b;
  ^