foo.c: In function 'main':
foo.c:5:14: warning: unused variable 'vleft' [-Wunused-variable]
    5 |     long int vleft=V,dp[20010];//空间优化的0-1背包
      |              ^~~~~
foo.c:4:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    4 |     scanf("%ld%ld",&V,&n);
      |     ^~~~~~~~~~~~~~~~~~~~~
foo.c:7:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    7 |         scanf("%ld",&v[i]);
      |         ^~~~~~~~~~~~~~~~~~

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