Compilare: user.cpp: In function ‘void modify()’: user.cpp:63:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<=s.size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:100:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bool.in", "r", stdin); ^ user.cpp:101:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bool.out", "w", stdout); ^ user.cpp:106:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d ", &n); ^ user.cpp:111:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c", &c); ^