Compilare: user.cpp: In function ‘int main()’: user.cpp:37:15: warning: unused variable ‘j’ [-Wunused-variable] int n, i, j, ta, tb, max=-1, l, c; ^ user.cpp:36:33: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, 20000, stdin); ^ user.cpp: In function ‘void read(int&)’: user.cpp:28:102: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] while(buff[pos] < '0' || buff[pos] > '9')if(++pos == 20000) fread(buff, 1, 20000, stdin), pos = 0; ^ user.cpp:30:137: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] while('0' <= buff[pos] && buff[pos] <= '9') {nr = nr * 10 + buff[pos] - '0';if(++pos == 20000) fread(buff, 1, 20000, stdin), pos = 0;} ^