Compilare: user.cpp: In function ‘int main()’: user.cpp:49:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<S.length();i++) ^ user.cpp:53:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=k-1;i<S.length();i++) ^ user.cpp:70:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<S.length();j++) ^ user.cpp:85:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=i;j<S.length();j++) ^ user.cpp:98:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int c=t+j+1;c<S.length();c++) ^ user.cpp:125:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=i;j<S.length();j++) ^