{"raw_statement":[{"iden":"problem statement","content":"There are $N+1$ towns. The $i$\\-th town is being attacked by $A_i$ monsters.\nWe have $N$ heroes. The $i$\\-th hero can defeat monsters attacking the $i$\\-th or $(i+1)$\\-th town, for a total of at most $B_i$ monsters.\nWhat is the maximum total number of monsters the heroes can cooperate to defeat?"},{"iden":"constraints","content":"*   All values in input are integers.\n*   $1 \\leq N \\leq 10^5$\n*   $1 \\leq A_i \\leq 10^9$\n*   $1 \\leq B_i \\leq 10^9$"},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$\n$A_1$ $A_2$ $...$ $A_{N+1}$\n$B_1$ $B_2$ $...$ $B_N$"},{"iden":"sample input 1","content":"2\n3 5 2\n4 5"},{"iden":"sample output 1","content":"9\n\nIf the heroes choose the monsters to defeat as follows, they can defeat nine monsters in total, which is the maximum result.\n\n*   The first hero defeats two monsters attacking the first town and two monsters attacking the second town.\n*   The second hero defeats three monsters attacking the second town and two monsters attacking the third town."},{"iden":"sample input 2","content":"3\n5 6 3 8\n5 100 8"},{"iden":"sample output 2","content":"22"},{"iden":"sample input 3","content":"2\n100 1 1\n1 100"},{"iden":"sample output 3","content":"3"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}