View Compilation Error

0_0_18414799_30845.cpp: In function 'int solve()':
0_0_18414799_30845.cpp:49:29: error: 'first' was not declared in this scope
     if(b[1]-a[1]==1) return first;
                             ^
0_0_18414799_30845.cpp:54:19: error: 'first' was not declared in this scope
     if(sg) return first;
                   ^
0_0_18414799_30845.cpp:55:17: error: 'first' was not declared in this scope
     else return first^1;
                 ^