{"raw_statement":[{"iden":"problem statement","content":"$N$ persons are standing in a row. The height of the $i$\\-th person from the front is $A_i$.\nWe want to have each person stand on a stool of some heights - at least zero - so that the following condition is satisfied for every person:\nCondition: Nobody in front of the person is taller than the person. Here, the height of a person includes the stool.\nFind the minimum total height of the stools needed to meet this goal."},{"iden":"constraints","content":"*   $1 \\leq N \\leq 2\\times 10^5$\n*   $1 \\leq A_i \\leq 10^9$\n*   All values in input are integers."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$\n$A_1$ $\\ldots$ $A_N$"},{"iden":"sample input 1","content":"5\n2 1 5 4 3"},{"iden":"sample output 1","content":"4\n\nIf the persons stand on stools of heights $0$, $1$, $0$, $1$, and $2$, respectively, their heights will be $2$, $2$, $5$, $5$, and $5$, satisfying the condition.\nWe cannot meet the goal with a smaller total height of the stools."},{"iden":"sample input 2","content":"5\n3 3 3 3 3"},{"iden":"sample output 2","content":"0\n\nGiving a stool of height $0$ to everyone will work."}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}