/in/foo.cc:9:53: error: expected unqualified-id before '.' token
 int s[100005][2],sum[100005][2],c[100005],x[100005];.//定义二维数组方便分组
                                                     ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:12:21: error: 'n' was not declared in this scope
     scanf ("%d %d",&n,&m);//其实m没有什么用处
                     ^
/in/foo.cc:12:24: error: 'm' was not declared in this scope
     scanf ("%d %d",&n,&m);//其实m没有什么用处
                        ^
/in/foo.cc:22:9: error: 'ans' was not declared in this scope
         ans=(ans+i*((s[c[i]][i%2]-2)*x[i]%10007+sum[c[i]][i%2]))%10007;//依次然后代入，注意，也要mod10007
         ^~~
/in/foo.cc:24:20: error: 'ans' was not declared in this scope
     printf ("%d\n",ans);//最后输出
                    ^~~