Compilare: main.cpp: In function 'void readc(T&) [with T = int]': main.cpp:61:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v); ^ main.cpp: In function 'void readc(T&) [with T = char]': main.cpp:66:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf(" %c", &v); // remove white space before %c if you want to include whitespaces ^ main.cpp: In function 'void readc(T&) [with T = long long int]': main.cpp:71:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%lld", &v); ^ main.cpp: In function 'void readc(T&) [with T = float]': main.cpp:76:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%f", &v); ^ main.cpp: In function 'void readc(T&) [with T = double]': main.cpp:81:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%lf", &v); ^ main.cpp: In function 'void readc(T&) [with T = char*]': main.cpp:91:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%s", str); ^ main.cpp: In function 'int main()': main.cpp:25:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen(nm ".in", "r", stdin); \ ^ main.cpp:204:5: note: in expansion of macro 'PB_FILE' PB_FILE("cmlsc"); ^~~~~~~ main.cpp:204:21: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] PB_FILE("cmlsc"); ^ main.cpp:214:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:217:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", a + i); ^ main.cpp:221:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", b + i); ^