foo.cpp:5:34: error: 'int y0' redeclared as different kind of symbol
 int f[2][105][105][4],ans,n,m,x0,y0;
                                  ^
In file included from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\cmath:44:0,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\random:38,
                 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:2:
c:\mingw\include\math.h:262:24: error: previous declaration of 'double y0(double)'
 _CRTIMP double __cdecl y0 (double);
                        ^
foo.cpp: In function 'int main()':
foo.cpp:13:32: warning: format '%d' expects argument of type 'int*', but argument 5 has type 'double (__attribute__((__cdecl__)) *)(double)' [-Wformat=]
  scanf("%d%d%d%d",&n,&m,&x0,&y0);
                                ^
foo.cpp:16:17: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'char (*)[105]' [-Wformat=]
   scanf("%s",&ch);
                 ^
foo.cpp:21:13: error: invalid types 'int [105][4][double(double)]' for array subscript
  f[0][x0][y0][0]=0;
             ^