View Compilation Error

0_0_33178812_10104.cpp: In function 'int main()':
0_0_33178812_10104.cpp:180:52: error: 'so' was not declared in this scope
         int ind = unique(sol.begin(), sol.end()) - so
                                                    ^
0_0_33178812_10104.cpp:180:52: error: expected ',' or ';' at end of input
0_0_33178812_10104.cpp:180:52: error: expected '}' at end of input
0_0_33178812_10104.cpp:180:52: error: expected '}' at end of input