foo.c: In function 'main':
foo.c:9:7: warning: unused variable 'p1' [-Wunused-variable]
  int* p1 = (int*)malloc(4 * n);
       ^~
foo.c:6:8: warning: unused variable 'm' [-Wunused-variable]
  int n,m=0,re=-10000;
        ^
foo.c:7:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
  ^~~~~~~~~~~~~~~
foo.c:12:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &p[i]);
   ^~~~~~~~~~~~~~~~~~

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