Main.cc: In function 'int main()':
Main.cc:19:26: error: 'n' was not declared in this scope
printf("%.2f%%\n",q*1.0/n*100);
^
Main.cc:5:15: warning: unused variable 'sum' [-Wunused-variable]
int a,b[101],sum=0,q=0,w=0,e=0,r=0;
^