Compilare: user.cpp: In function ‘int main()’: user.cpp:14:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<n;++i){ ^ user.cpp:33:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<x;++i){ ^ user.cpp:46:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<x;++i){ ^ user.cpp:59:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<x;++i){ ^ user.cpp:73:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<x;++i){ ^ user.cpp:9:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("z.in", "r", stdin); ^ user.cpp:10:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("z.out", "w", stdout); ^ user.cpp:12:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &k); ^ user.cpp:25:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x,&y); ^