Compilare: user.cpp: In function ‘bool cmp_line(line, line)’: user.cpp:16:38: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] return ( a.b < b.b || a.a == b.a && a.a < b.a || a.a == b.a && a.b == b.b && a.i < b.i ); ^ user.cpp:16:79: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] return ( a.b < b.b || a.a == b.a && a.a < b.a || a.a == b.a && a.b == b.b && a.i < b.i ); ^ user.cpp: In function ‘int main()’: user.cpp:59:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while ( i < d.size() - 1 && int_line( d[i], d[i + 1] ) < t ) ^ user.cpp:32:24: warning: unused variable ‘l’ [-Wunused-variable] int n, m, i, j, t, l; ^