{"problem":{"name":"Prison","description":{"content":"We have $N$ ID cards, and there are $M$ gates. We can pass the $i$\\-th gate if we have one of the following ID cards: the $L_i$\\-th, $(L_i+1)$\\-th, ..., and $R_i$\\-th ID cards. How many of the ID card","description_type":"Markdown"},"platform":"AtCoder","limit":{"time_limit":2000,"memory_limit":262144},"difficulty":"None","is_remote":true,"is_sync":true,"sync_url":null,"sign":"abc127_c"},"statements":[{"statement_type":"Markdown","content":"We have $N$ ID cards, and there are $M$ gates.\nWe can pass the $i$\\-th gate if we have one of the following ID cards: the $L_i$\\-th, $(L_i+1)$\\-th, ..., and $R_i$\\-th ID cards.\nHow many of the ID cards allow us to pass all the gates alone?\n\n## Constraints\n\n*   All values in input are integers.\n*   $1 \\leq N \\leq 10^5$\n*   $1 \\leq M \\leq 10^5$\n*   $1 \\leq L_i \\leq R_i \\leq N$\n\n## Input\n\nInput is given from Standard Input in the following format:\n\n$N$ $M$\n$L_1$ $R_1$\n$L_2$ $R_2$\n$\\vdots$\n$L_M$ $R_M$\n\n[samples]","is_translate":false,"language":"English"}],"meta":{"iden":"abc127_c","tags":[],"sample_group":[["4 2\n1 3\n2 4","2\n\nTwo ID cards allow us to pass all the gates alone, as follows:\n\n*   The first ID card does not allow us to pass the second gate.\n*   The second ID card allows us to pass all the gates.\n*   The third ID card allows us to pass all the gates.\n*   The fourth ID card does not allow us to pass the first gate."],["10 3\n3 6\n5 7\n6 9","1"],["100000 1\n1 100000","100000"]],"created_at":"2026-03-03 11:01:14"}}