Compilare: user.cpp: In function ‘bool pairup(int)’: user.cpp:21:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < A[x].size(); i++) { ^ user.cpp:23:13: warning: unused variable ‘idx’ [-Wunused-variable] int idx = A[x][i].second; ^ user.cpp:31:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < A[x].size(); i++) { ^ user.cpp:33:13: warning: unused variable ‘idx’ [-Wunused-variable] int idx = A[x][i].second; ^ user.cpp: In function ‘int main()’: user.cpp:60:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("circulatie.in", "r", stdin); ^ user.cpp:61:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("circulatie.out", "w", stdout); ^ user.cpp:63:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:65:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^