foo.cc: In function 'int main()':
foo.cc:8:21: error: 'z' was not declared in this scope
     cin >> n >> y >>z;
                     ^
foo.cc:10:9: error: 'i' was not declared in this scope
     for(i=0,i<=y,i++)
         ^
foo.cc:15:5: error: expected primary-expression before 'return'
     return 0;
     ^~~~~~
foo.cc:15:5: error: expected ')' before 'return'
foo.cc:5:9: warning: unused variable 'a' [-Wunused-variable]
     int a[]={31,28,31,30,31,30,31,31,30,31,30,31}; 
         ^

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