Compilare: user.cpp: In function ‘int main()’: user.cpp:24:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<=a.length(); i++){ ^ user.cpp:25:30: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if(a[i-1] > a[i] and a[i] < a[i+1] or a[i-1] < a[i] and a[i] > a[i+1]){ ^ user.cpp:49:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<a.length(); i++){ ^