/in/foo.cc:1:9: error: #include expects "FILENAME" or <FILENAME>
 #include
         ^
/in/foo.cc:5:1: error: 'ifstream' does not name a type
 ifstream fin("a.in");
 ^~~~~~~~
/in/foo.cc:7:1: error: 'ofstream' does not name a type
 ofstream fout("a.out");
 ^~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:15:1: error: 'cin' was not declared in this scope
 cin>>m;
 ^~~
/in/foo.cc:19:10: error: invalid operands of types 'int' and 'int [1001]' to binary 'operator-'
 b[i]=a[i]-a;
      ~~~~^~
/in/foo.cc:13:7: warning: unused variable 'j' [-Wunused-variable]
 int i,j,m,a[1001]={0},b[1001]={0};
       ^