/in/foo.cc: In function 'int main()':
/in/foo.cc:20:22: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'char (*)[10000001]' [-Wformat=]
         scanf("%s",&c);
                      ^
/in/foo.cc:21:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=0;i<=strlen(c)-1;i++)//因为前面输入过第一位数，故只从长度-1位开始输入； 
                     ~^~~~~~~~~~~~~