Compilare: main.cpp: In function 'std::__cxx11::string perm(long long int)': main.cpp:18:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i <=c; i++) { ~~^~~ main.cpp:20:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < n; j++) { ~~^~~ main.cpp: In function 'int main()': main.cpp:50:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < n; i++) { ~~^~~ main.cpp:63:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i <= c; i++) { ~~^~~~ main.cpp:65:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 2; j <= c; j++) { ~~^~~~ main.cpp:72:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < n; i++) { ~~^~~ main.cpp:75:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 2; j <= c; j++) { ~~^~~~ main.cpp:83:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i <= c; i++) ~~^~~~ main.cpp:90:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < n; i++) ~~^~~ main.cpp:98:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < n; i++) ~~^~~