Compilare: user.cpp: In function ‘void df(int, int)’: user.cpp:14:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i < g[a].size() ; ++i) ^ user.cpp:24:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i < g[a].size() ; ++i) ^ user.cpp: In function ‘void solve(int)’: user.cpp:33:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i < g[a].size() ; ++i) ^ user.cpp:39:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i < g[a].size() ; ++i) ^ user.cpp:49:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == g[a].size() - 1) ir[i] = (d[b][0] + d[b][1]) % mod; ^ user.cpp:64:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i < g[a].size() ; ++i) ^ user.cpp:70:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i < g[a].size() - 1) add = (1LL * add * ir[i + 1]) % mod; ^ user.cpp: In function ‘int main()’: user.cpp:79:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("karb2.in" , "r" , stdin); ^ user.cpp:80:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("karb2.out" , "w" , stdout); ^ user.cpp:82:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &n); ^ user.cpp:83:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &k); ^ user.cpp:87:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &x); ^ user.cpp:93:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &x); ^ user.cpp:94:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &y); ^