/in/foo.cc: In function 'bool hw(int)':
/in/foo.cc:10:9: warning: unused variable 'k' [-Wunused-variable]
 int i,j,k;  
         ^
/in/foo.cc: In function 'void rd()':
/in/foo.cc:24:1: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
 if(isdigit(s[i]))j=s[i]-'0';      if(islower(s[i]))j=s[i]-'a'+10;      if(isupper(s[i]))j=s[i]-'A'+10;      
 ^~
/in/foo.cc:24:35: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if'
 if(isdigit(s[i]))j=s[i]-'0';      if(islower(s[i]))j=s[i]-'a'+10;      if(isupper(s[i]))j=s[i]-'A'+10;      
                                   ^~
/in/foo.cc: In function 'void add(int)':
/in/foo.cc:30:9: warning: unused variable 'k' [-Wunused-variable]
 int i,j,k,last,y=1-x;  
         ^
/in/foo.cc: In function 'void rd()':
/in/foo.cc:25:16: warning: 'j' may be used uninitialized in this function [-Wmaybe-uninitialized]
 a[0][++a[0][0]]=j;    
 ~~~~~~~~~~~~~~~^~