foo.cpp: In function 'int main()':
foo.cpp:13:19: error: expected primary-expression before '>' token
   if (tot>0&&a[i]=>s[tot]) --tot;
                   ^
foo.cpp:16:22: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
   if (s[tot]^s[tot-1]>ans) ans=s[tot]^s[tot-1];
                      ^
foo.cpp:6:8: warning: unused variable 'j' [-Wunused-variable]
  int i,j,k,n,tot,ans=0;
        ^
foo.cpp:6:10: warning: unused variable 'k' [-Wunused-variable]
  int i,j,k,n,tot,ans=0;
          ^