View Compilation Error

0_0_28056120_10555.cpp:25:8: error: 'll' was not declared in this scope
 int ch(ll mid)
        ^
0_0_28056120_10555.cpp:26:1: error: expected ',' or ';' before '{' token
 {
 ^
0_0_28056120_10555.cpp: In function 'int main()':
0_0_28056120_10555.cpp:44:3: error: 'll' was not declared in this scope
   ll l=0,r=mx,mid,ans=-1;
   ^
0_0_28056120_10555.cpp:45:9: error: 'l' was not declared in this scope
   while(l<=r)
         ^
0_0_28056120_10555.cpp:45:12: error: 'r' was not declared in this scope
   while(l<=r)
            ^
0_0_28056120_10555.cpp:47:4: error: 'mid' was not declared in this scope
    mid=l+r>>1;
    ^
0_0_28056120_10555.cpp:48:13: error: 'ch' cannot be used as a function
    if(ch(mid))
             ^
0_0_28056120_10555.cpp:51:5: error: 'ans' was not declared in this scope
     ans=mid;
     ^
0_0_28056120_10555.cpp:56:19: error: 'ans' was not declared in this scope
   printf("%lld\n",ans);
                   ^