View Compilation Error

0_0_22050100_27032.cpp: In function 'int main()':
0_0_22050100_27032.cpp:141:19: error: invalid conversion from 'unsigned char*' to 'const char*' [-fpermissive]
         n=strlen(s);
                   ^
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/cstring:42:0,
                 from 0_0_22050100_27032.cpp:3:
GCC4.9.2/x86_64-w64-mingw32/include/string.h:54:18: note: initializing argument 1 of 'size_t strlen(const char*)'
   size_t __cdecl strlen(const char *_Str);
                  ^