foo.cc: In function 'int combination(int, int)':
foo.cc:62:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=0;i<prim.size()&&prim[i]<=n;++i)
                     ~^~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:72:15: warning: value computed is not used [-Wunused-value]
         while(~scanf("%d%d",&m,&n),m&&n)
               ^~~~~~~~~~~~~~~~~~~~

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