foo.cc: In function 'int main()':
foo.cc:15:9: error: expected primary-expression before 'return'
   15 |         return 0;
      |         ^~~~~~
foo.cc:6:13: warning: unused variable 'a' [-Wunused-variable]
    6 |         int a[MAXN],b[MAXN],s[MAXN];
      |             ^
foo.cc:6:29: warning: unused variable 's' [-Wunused-variable]
    6 |         int a[MAXN],b[MAXN],s[MAXN];
      |                             ^
foo.cc:7:17: warning: unused variable 'x' [-Wunused-variable]
    7 |         int n,k,x;
      |                 ^

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