Compilare: user.cpp: In function ‘int main()’: user.cpp:25:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (participants[c].size() > max1) { ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~ user.cpp:30:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] } else if (participants[c].size() > max2) { ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~ user.cpp:5:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("concurs2.in", "r", stdin); ^ user.cpp:6:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("concurs2.out", "w", stdout); ^ user.cpp:8:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:12:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^