Compilare: main.cpp: In function 'int main()': main.cpp:49:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v.size(); i++) ~~^~~~~~~~~~ main.cpp: In function 'int scan()': main.cpp:21:107: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] while(b[p] != '-' and !('0' <= b[p] and b[p] <= '9')) { p++; if(p == mx) fread(b, 1, mx, stdin), p = 0; } ^ main.cpp:22:77: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] if(b[p] == '-') { f = -1, p++; if(p == mx) fread(b, 1, mx, stdin), p = 0; } ^ main.cpp:23:115: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] while('0' <= b[p] and b[p] <= '9') { nr = nr * 10 + b[p] - '0', p++; if(p == mx) fread(b, 1, mx, stdin), p = 0; } ^ main.cpp: In function 'int main()': main.cpp:31:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("rays.in", "r", stdin); ^ main.cpp:32:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("rays.out", "w", stdout); ^ main.cpp:35:27: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(b, 1, mx, stdin); ^