#define NULL ((void *)0)
typedef unsigned long size_t; // Customize by platform.
typedef long intptr_t;
typedef unsigned long uintptr_t;
typedef long scalar_t__; // Either arithmetic or pointer type.
/* By default, we understand bool (as a convenience). */
typedef int bool;
#define false 0
#define true 1

/* Forward declarations */

/* Type definitions */

/* Variables and functions */
int /*<<< orphan*/ printf(char *, int);
int /*<<< orphan*/ scanf(char *, int *, ...);
int main() {
  int n, i, t = 0, s = 0, a, b;
  scanf("%d", &n);
  for (i = 1; i <= n; i++) {
    scanf("%d %d", &a, &b);
    t += b - a;
    if (t > s)
      s = t;
  }
  printf("%d\n", s);
  return 0;
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
movl   $0x0,-0x4(%rbp)
movl   $0x0,-0x10(%rbp)
movl   $0x0,-0x14(%rbp)
lea    0xebf(%rip),%rdi
lea    -0x8(%rbp),%rsi
mov    $0x0,%al
call   1040 <scanf@plt>
movl   $0x1,-0xc(%rbp)
mov    -0xc(%rbp),%eax
cmp    -0x8(%rbp),%eax
jg     11a9 <main+0x89>
lea    0xe97(%rip),%rdi
lea    -0x18(%rbp),%rsi
lea    -0x1c(%rbp),%rdx
mov    $0x0,%al
call   1040 <scanf@plt>
mov    -0x1c(%rbp),%eax
sub    -0x18(%rbp),%eax
add    -0x10(%rbp),%eax
mov    %eax,-0x10(%rbp)
mov    -0x10(%rbp),%eax
cmp    -0x14(%rbp),%eax
jle    1196 <main+0x76>
mov    -0x10(%rbp),%eax
mov    %eax,-0x14(%rbp)
jmp    119b <main+0x7b>
mov    -0xc(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0xc(%rbp)
jmp    1156 <main+0x36>
mov    -0x14(%rbp),%esi
lea    0xe53(%rip),%rdi
call   1030 <printf@plt>
xor    %eax,%eax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %rbp
push   %r15
push   %r14
push   %r13
push   %r12
push   %rbx
sub    $0x18,%rsp
lea    0xece(%rip),%rdi
xor    %r13d,%r13d
lea    0xc(%rsp),%rsi
xor    %eax,%eax
call   1040 <scanf@plt>
cmpl   $0x0,0xc(%rsp)
jle    119a <main+0x7a>
lea    0xeae(%rip),%r14
lea    0x14(%rsp),%r15
lea    0x10(%rsp),%r12
xor    %ebp,%ebp
xor    %r13d,%r13d
xor    %ebx,%ebx
cs nopw 0x0(%rax,%rax,1)
nopl   (%rax)
mov    %r14,%rdi
mov    %r15,%rsi
mov    %r12,%rdx
xor    %eax,%eax
call   1040 <scanf@plt>
mov    0x10(%rsp),%eax
sub    0x14(%rsp),%eax
add    %eax,%ebx
cmp    %r13d,%ebx
cmovg  %ebx,%r13d
add    $0x1,%ebp
cmp    0xc(%rsp),%ebp
jl     1170 <main+0x50>
lea    0xe65(%rip),%rdi
mov    %r13d,%esi
call   1030 <printf@plt>
xor    %eax,%eax
add    $0x18,%rsp
pop    %rbx
pop    %r12
pop    %r13
pop    %r14
pop    %r15
pop    %rbp
ret

LLVM IR (-O0):
@.str = [3 x i8] c"%d\00"
@.str.1 = [6 x i8] c"%d %d\00"
@.str.2 = [4 x i8] c"%d\0A\00"
define i32 @main() {
%1 = alloca i32
%2 = alloca i32
%3 = alloca i32
%4 = alloca i32
%5 = alloca i32
%6 = alloca i32
%7 = alloca i32
store i32 0, i32* %1
store i32 0, i32* %4
store i32 0, i32* %5
%8 = call i32 (i8*, i32*, ...) @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i32* %2)
store i32 1, i32* %3
br label %9
9: ; preds = %26, %0
%10 = load i32, i32* %3
%11 = load i32, i32* %2
%12 = icmp sle i32 %10, %11
br i1 %12, label %13, label %29
13: ; preds = %9
%14 = call i32 (i8*, i32*, ...) @scanf(i8* getelementptr inbounds ([6 x i8], [6 x i8]* @.str.1, i64 0, i64 0), i32* %6, i32* %7)
%15 = load i32, i32* %7
%16 = load i32, i32* %6
%17 = sub nsw i32 %15, %16
%18 = load i32, i32* %4
%19 = add nsw i32 %18, %17
store i32 %19, i32* %4
%20 = load i32, i32* %4
%21 = load i32, i32* %5
%22 = icmp sgt i32 %20, %21
br i1 %22, label %23, label %25
23: ; preds = %13
%24 = load i32, i32* %4
store i32 %24, i32* %5
br label %25
25: ; preds = %23, %13
br label %26
26: ; preds = %25
%27 = load i32, i32* %3
%28 = add nsw i32 %27, 1
store i32 %28, i32* %3
br label %9
29: ; preds = %9
%30 = load i32, i32* %5
%31 = call i32 @printf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.2, i64 0, i64 0), i32 %30)
ret i32 0
}

LLVM IR (-O2):
@.str = [3 x i8] c"%d\00"
@.str.1 = [6 x i8] c"%d %d\00"
@.str.2 = [4 x i8] c"%d\0A\00"
define i32 @main() {
%1 = alloca i32
%2 = alloca i32
%3 = alloca i32
%4 = bitcast i32* %1 to i8*
%5 = bitcast i32* %2 to i8*
%6 = bitcast i32* %3 to i8*
%7 = call i32 (i8*, i32*, ...) @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i32* %1)
%8 = load i32, i32* %1
%9 = icmp slt i32 %8, 1
br i1 %9, label %24, label %10
10: ; preds = %0, %10
%11 = phi i32 [ %20, %10 ], [ 0, %0 ]
%12 = phi i32 [ %18, %10 ], [ 0, %0 ]
%13 = phi i32 [ %21, %10 ], [ 1, %0 ]
%14 = call i32 (i8*, i32*, ...) @scanf(i8* getelementptr inbounds ([6 x i8], [6 x i8]* @.str.1, i64 0, i64 0), i32* %2, i32* %3)
%15 = load i32, i32* %3
%16 = load i32, i32* %2
%17 = sub nsw i32 %15, %16
%18 = add nsw i32 %17, %12
%19 = icmp sgt i32 %18, %11
%20 = select i1 %19, i32 %18, i32 %11
%21 = add nuw nsw i32 %13, 1
%22 = load i32, i32* %1
%23 = icmp slt i32 %13, %22
br i1 %23, label %10, label %24
24: ; preds = %10, %0
%25 = phi i32 [ 0, %0 ], [ %20, %10 ]
%26 = call i32 @printf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.2, i64 0, i64 0), i32 %25)
ret i32 0
}