Compilare: user.cpp: In function ‘int main()’: user.cpp:78:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0, val=0; i < bands.size(); i++, val++) ^ user.cpp:85:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0, val=0; i < bands.size(); i++, val++) ^ user.cpp:102:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; j < bands.size() && bands[j].nr == i; j++) ^ user.cpp:68:28: warning: unused variable ‘k’ [-Wunused-variable] int n, i, val, cpy, j, k; ^ user.cpp:65:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("heavymetal.in", "r", stdin); ^ user.cpp:66:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("heavymetal.out", "w", stdout); ^ user.cpp:70:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:73:48: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &band.left, &band.right); ^