litere.cpp: In function `void vocale()': litere.cpp:15: warning: comparison between signed and unsigned integer expressions litere.cpp:19: warning: comparison between signed and unsigned integer expressions litere.cpp: In function `void val()': litere.cpp:35: warning: comparison between signed and unsigned integer expressions litere.cpp:37: warning: comparison between signed and unsigned integer expressions litere.cpp:41: warning: comparison between signed and unsigned integer expressions litere.cpp: In function `void calcul()': litere.cpp:50: warning: unused variable `int sum'