const std = @import("std");

const mem = std.mem;
const fmt = std.fmt;

const input = @embedFile("input");

pub fn main() !void {
    var count: usize = 0;
    // Iterate through the lines
    var lines = mem.split(u8, input, "\n");
    while (lines.next()) |line| {
        // If line is empty, ignore
        if (line.len == 0) continue;

        var limits: [2][2]usize = undefined;

        //std.debug.print("{s}\n", .{line});

        // Which elf
        var elf: usize = 0;
        // Which limit
        var limit: usize = 0;
        // Start of slice
        var start: usize = 0;

        for (line) |char, index| {
            if (char == '-') {

                const number = fmt.parseInt(usize, line[start..index], 10) catch 0;
                //std.debug.print("{}\n", .{number});
                limits[elf][limit] = number;
                start = index + 1;
                limit += 1;

                // 10-20,30-40
                //    ^

            }
            if (char == ',') {

                const number = fmt.parseInt(usize, line[start..index], 10) catch 0;
                //std.debug.print("{}\n", .{number});
                limits[elf][limit] = number;
                start = index + 1;
                elf += 1;
                limit = 0;

                // 10-20,30-40
                //       ^

            }
            if (index == line.len - 1) {

                const number = fmt.parseInt(usize, line[start..], 10) catch 0;
                //std.debug.print("{}\n", .{number});
                limits[elf][limit] = number;

            }
        }

        // Check if they overlap
        if ((limits[0][0] >= limits[1][0] and limits[0][0] <= limits[1][1]) or
            (limits[1][0] >= limits[0][0] and limits[1][0] <= limits[0][1])) {
           count += 1;
        }
    }

    std.debug.print("{}\n", .{count});
}