foo.cc: In function 'void write(ll, char)':
foo.cc:26:13: warning: array subscript has type 'char' [-Wchar-subscripts]
     do a[++s]=x%10|48;while(x/=10);
             ^
foo.cc:27:19: warning: array subscript has type 'char' [-Wchar-subscripts]
     do putchar(a[s]);while(--s);
                   ^
foo.cc: In function 'void build(int, int, int)':
foo.cc:36:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
         int m=l+r>>1;
               ~^~
foo.cc: In function 'void add(int, int, int, int, int, ll)':
foo.cc:56:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
         int m=l+r>>1;
               ~^~
foo.cc: In function 'll ask(int, int, int, int, int)':
foo.cc:69:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
         int m=l+r>>1;
               ~^~

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