/in/foo.cc: In function 'int main()':
/in/foo.cc:14:15: warning: right operand of comma operator has no effect [-Wunused-value]
     cin>>n1,n2;
               ^
/in/foo.cc:15:23: warning: 'n2' is used uninitialized in this function [-Wuninitialized]
     int a[n1]={0},b[n2]={0};
                       ^