Compilare: user.cpp: In function ‘void solve()’: user.cpp:72:13: warning: unused variable ‘mid’ [-Wunused-variable] int l, r, mid; ^~~ user.cpp: In function ‘void read()’: user.cpp:20:45: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf (fin, "%d%d%lld%d", &n, &m, &c, &r); ^ user.cpp:21:59: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf (fin, "%lld%lld%lld%lld%lld", &x, &y, &z, &w, &u); ^ user.cpp:23:33: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf (fin, "%d", &a[1][i]); ^ user.cpp:25:33: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf (fin, "%d", &a[i][1]); ^