Compilare: main.cpp: In function 'int main()': main.cpp:163:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("prefix2.in", "r", stdin); ^ main.cpp:165:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("prefix2.out", "w", stdout); ^ main.cpp:169:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%s", s + 1); int n = strlen(s + 1); ^