{"raw_statement":[{"iden":"problem statement","content":"In a public bath, there is a shower which emits water for $T$ seconds when the switch is pushed.\nIf the switch is pushed when the shower is already emitting water, from that moment it will be emitting water for $T$ seconds. Note that it does not mean that the shower emits water for $T$ additional seconds.\n$N$ people will push the switch while passing by the shower. The $i$\\-th person will push the switch $t_i$ seconds after the first person pushes it.\nHow long will the shower emit water in total?"},{"iden":"constraints","content":"*   $1 ≤ N ≤ 200,000$\n*   $1 ≤ T ≤ 10^9$\n*   $0 = t_1 < t_2 < t_3 < , ..., < t_{N-1} < t_N ≤ 10^9$\n*   $T$ and each $t_i$ are integers."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$ $T$\n$t_1$ $t_2$ ... $t_N$"},{"iden":"sample input 1","content":"2 4\n0 3"},{"iden":"sample output 1","content":"7\n\nThree seconds after the first person pushes the water, the switch is pushed again and the shower emits water for four more seconds, for a total of seven seconds."},{"iden":"sample input 2","content":"2 4\n0 5"},{"iden":"sample output 2","content":"8\n\nOne second after the shower stops emission of water triggered by the first person, the switch is pushed again."},{"iden":"sample input 3","content":"4 1000000000\n0 1000 1000000 1000000000"},{"iden":"sample output 3","content":"2000000000"},{"iden":"sample input 4","content":"1 1\n0"},{"iden":"sample output 4","content":"1"},{"iden":"sample input 5","content":"9 10\n0 3 5 7 100 110 200 300 311"},{"iden":"sample output 5","content":"67"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}