Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:27:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( int i= 0; i<v[p].size(); ++i ) { ^ user.cpp: In function ‘int main()’: user.cpp:58:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( int j= 0; j<v[i].size(); ++j ) { ^ user.cpp:59:43: warning: suggest parentheses around comparison in operand of ‘^’ [-Wparentheses] if ( sol[i]^sol[v[i][j].x]!=v[i][j].y ) { ^