Compilare: user.cpp: In function ‘void read()’: user.cpp:28:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<a.size(); i++) ^ user.cpp:40:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<a.size(); i++) ^ user.cpp:43:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<a[i].size(); j++) ^ user.cpp: In function ‘void sp(int)’: user.cpp:54:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (; i<a.size(); i++) ^ user.cpp:58:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i==a.size() || ez(a[i][x])) ^ user.cpp: In function ‘void adun(int)’: user.cpp:69:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=x+1; i<a.size(); i++) ^ user.cpp:72:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=x; j<a[i].size(); j++) ^ user.cpp: In function ‘void solve()’: user.cpp:81:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<a.size(); i++) ^ user.cpp: In function ‘void write()’: user.cpp:98:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<a.size(); j++) ^ user.cpp: At global scope: user.cpp:112:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^