Compilare: main.cpp: In function 'int main()': main.cpp:11:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < N; i++) ~~^~~ main.cpp:12:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < M; j++) ~~^~~ main.cpp:19:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < N; i++) ~~^~~ main.cpp:21:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < M; j++) ~~^~~ main.cpp:24:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int r = 0; r < N; r++) ~~^~~ main.cpp:27:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int c = 0; c < M; c++) ~~^~~ main.cpp:39:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < N; i++) ~~^~~ main.cpp:42:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < M; j++) ~~^~~ main.cpp:46:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < N; i++) ~~^~~ main.cpp:47:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < M; j++) ~~^~~ main.cpp:17:9: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized] int x, y; ^ main.cpp:40:21: warning: 'y' may be used uninitialized in this function [-Wmaybe-uninitialized] table[i][y] *= -1; ~~~~~~~~~~~~^~~~~