foo.cc: In function 'void solve()':
foo.cc:20:9: error: 'a' was not declared in this scope
    cin>>a[i][j];
         ^
foo.cc:27:8: error: 'a' was not declared in this scope
     if(a[i+1][j]>a[i][j+1]) dp[i+1][j]=dp[i][j]-a[i+1][j];
        ^
foo.cc:31:25: error: 'a' was not declared in this scope
     dp[i+1][j]=dp[i][j]+a[i+1][j];
                         ^
foo.cc: At global scope:
foo.cc:36:3: error: 'cout' does not name a type
 } cout<<dp[n-1][m-1];
   ^~~~

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