Compilare: user.cpp: In function ‘void det_ans()’: user.cpp:109:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < Vx[i].size(); ++ j) ^ user.cpp:110:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (k = j + 1; k < Vx[i].size(); ++ k) ^ user.cpp:113:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < Vx[i].size(); ++ j) ^ user.cpp:114:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (k = 0; k < Vy[i].size(); ++ k) ^ user.cpp:117:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < Vy[i].size(); ++ j) ^ user.cpp:118:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (k = j + 1; k < Vy[i].size(); ++ k) ^ user.cpp: In function ‘void solve()’: user.cpp:126:9: warning: unused variable ‘i’ [-Wunused-variable] int i; ^ user.cpp: In function ‘void read()’: user.cpp:13:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("copaci4.in", "r", stdin); ^ user.cpp:14:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:17:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i]); ^ user.cpp: In function ‘void write()’: user.cpp:133:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("copaci4.out", "w", stdout); ^