foo.cpp:31:12: warning: multi-character character constant [-Wmultichar]
     printf('%d',ans);
            ^
foo.cpp: In function 'int main()':
foo.cpp:31:20: error: invalid conversion from 'int' to 'const char*' [-fpermissive]
     printf('%d',ans);
                    ^
In file included from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\cstdio:42:0,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\random:39,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_algo.h:65,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\algorithm:62,
                 from foo.cpp:1:
c:\mingw\include\stdio.h:293:37: error:   initializing argument 1 of 'int printf(const char*, ...)' [-fpermissive]
 _CRTIMP int __cdecl __MINGW_NOTHROW printf (const char*, ...);
                                     ^