foo.cc: In function 'void djikstra()':
foo.cc:28:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=0;j<cost[u].size();j++){
                     ~^~~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:37:18: error: 'n' was not declared in this scope
     fill(dis,dis+n+1,maxn);
                  ^
foo.cc:37:18: note: suggested alternative: 'yn'
     fill(dis,dis+n+1,maxn);
                  ^
                  yn
foo.cc:38:15: error: lvalue required as increment operand
     fill(vi,vi++n+1,0);
               ^~

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