View Compilation Error

0_0_23714708_23863.cpp: In function 'int main()':
0_0_23714708_23863.cpp:26:27: error: lvalue required as left operand of assignment
             maxn<a && maxn=a;
                           ^
0_0_23714708_23863.cpp:27:27: error: lvalue required as left operand of assignment
             maxn<b && maxn=b;
                           ^
0_0_23714708_23863.cpp:28:30: error: could not convert 'uni(a, b)' from 'void' to 'bool'
             if (!err&&uni(a,b)) err=true;
                              ^