foo.cc: In function 'double Knapsack(int, int)':
foo.cc:19:9: warning: unused variable 'i' [-Wunused-variable]
     int i, j;
         ^
foo.cc:19:12: warning: unused variable 'j' [-Wunused-variable]
     int i, j;
            ^
foo.cc: In function 'int main()':
foo.cc:39:9: warning: unused variable 't' [-Wunused-variable]
     int t = 1;
         ^
foo.cc:42:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d", &V, &P, &Q);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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