foo.cpp:2:7: error: expected nested-name-specifier before 'namesapce'
 using namesapce std;
       ^
foo.cpp:2:7: error: 'namesapce' has not been declared
foo.cpp:2:17: error: expected ';' before 'std'
 using namesapce std;
                 ^
foo.cpp:2:17: error: 'std' does not name a type
foo.cpp: In function 'int main()':
foo.cpp:6:1: error: 'cin' was not declared in this scope
 cin>>a>>b;
 ^
foo.cpp:6:1: note: suggested alternative:
In file included from foo.cpp:1:0:
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^
foo.cpp:7:1: error: 'cout' was not declared in this scope
 cout<<(a*a-b*b)/(a-b)<<endl;
 ^
foo.cpp:7:1: note: suggested alternative:
In file included from foo.cpp:1:0:
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^
foo.cpp:7:24: error: 'endl' was not declared in this scope
 cout<<(a*a-b*b)/(a-b)<<endl;
                        ^
foo.cpp:7:24: note: suggested alternative:
In file included from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\iostream:39:0,
                 from foo.cpp:1:
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\ostream:564:5: note:   'std::endl'
     endl(basic_ostream<_CharT, _Traits>& __os)
     ^