foo.cc: In function 'int main()':
foo.cc:10:14: warning: unused variable 'd' [-Wunused-variable]
   10 |  int i,a,j,k,d,num=0,cnt=0;cin>>a;for(i=0;i<=a;i++)for(j=0;j<=a;j++)for(k=0;k<=a;k++)if(i*1+j*2+k*5==a)cnt++;cout<<cnt<<endl;
      |              ^
foo.cc:10:16: warning: unused variable 'num' [-Wunused-variable]
   10 |  int i,a,j,k,d,num=0,cnt=0;cin>>a;for(i=0;i<=a;i++)for(j=0;j<=a;j++)for(k=0;k<=a;k++)if(i*1+j*2+k*5==a)cnt++;cout<<cnt<<endl;
      |                ^~~

[Hydro](https://hydro.ac)提供评测服务