View Compilation Error

0_0_19344847_3939.cpp: In function 'int main()':
0_0_19344847_3939.cpp:63:8: error: 'F' was not declared in this scope
     if(F[i][j][k] || F[i][j][l] || F[i][j][m] || F[i][k][l] ||  
        ^