/in/foo.cc: In function 'int main()':
/in/foo.cc:10:55: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'char (*)[20]' [-Wformat=]
   scanf("%s %d %d %c %c %d",&s[i],&s1,&s2,&c1,&c2,&num);
                                                       ^
/in/foo.cc:6:37: warning: 'k' may be used uninitialized in this function [-Wmaybe-uninitialized]
     int n,sum=0,max=0,s1,s2,num,a,b,k;
                                     ^