Compilare: user.cpp: In function ‘long int ret_max(int)’: user.cpp:14:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<q[k].size(); i++) ^ user.cpp: In function ‘void dfs_till_x(int, int, int)’: user.cpp:25:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<q[k].size(); i++) ^ user.cpp:34:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<q[k].size(); i++) ^ user.cpp: In function ‘void dfs_from_x_to_1(int, int)’: user.cpp:46:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<q[k].size(); i++) ^ user.cpp:63:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<q[k].size(); i++) ^ user.cpp: In function ‘long int solve(int, int)’: user.cpp:84:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<q[y].size(); i++) max1=max(max1,val_max[q[y][i]]); ^